Abstract
OBJECTIVES:
This study sought to analyze the effects of resistance training on functional performance, lower-limb loading distribution and balance in older women with total knee arthroplasty (TKA) and osteoarthritis (OA) in the contralateral knee. In addition, this older knee OA and TKA group (OKG) was compared to older (OG) and young women (YG) without musculoskeletal diseases who underwent the same resistance training program.
METHODS:
Twenty-three women divided into OKG (N = 7), OG (N = 8) and YG (N = 8) had their functional performance, lower-limb loading distribution and balance compared before and after 13 weeks of a twice-weekly progressive resistance training program.
RESULTS:
At baseline, the OKG showed lower functional performance and unilateral balance, and impaired lower-limb loading distribution compared to the OG and the YG (p<0.05). After resistance training, the OKG showed improvements in functional performance (∼13% in sit-to-stand and rising from the floor, ∼16% in stair-climbing and ∼23% in 6-minute walking (6 MW)), unilateral balance (∼72% and ∼78% in TKA and OA leg, respectively) and lower-limb loading distribution, which were greater than those observed in the OG and the YG. The OKG showed post-training 6 MW performance similar to that of the OG at baseline. Sit-to-stand performance and unilateral stand balance were further restored to post-training levels of the OG and to baseline levels of the YG.
CONCLUSIONS:
Resistance training partially restored functional, balance and lower-limb loading deficits in older women with TKA and OA in the contralateral knee. These results suggest that resistance training may be an important tool to counteract mobility impairments commonly found in this population.
Balance; Elderly; Functional Performance; Osteoarthritis; Resistance Training; Total Knee Arthroplasty
INTRODUCTION
Knee osteoarthritis (OA) is a common age-related clinical condition that has a major
impact on function and independence (11. Bitton R. The economic burden of osteoarthritis.
Am J Manag Care. 2009;15(8 Suppl):S230-5.),
including limitations in walking, stair climbing, rising from a seated or prone
position and household chores (22. Felson DT. Clinical practice. Osteoarthritis of the
knee. N Engl J Med. 2006;354(8):841-8.
3. Guccione AA, Felson DT, Anderson JJ, Anthony JM, Zhang Y, Wilson
PW, et al. The effects of specific medical conditions on the functional
limitations of elders in the Framingham Study. Am J Public Health.
1994;84(3):351-8.
4. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
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Clin Orthop Relat Res. 2009;467(6):1493-500,
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-55. Whitney SL, Wrisley DM, Marchetti GF, Gee MA, Redfern MS, Furman
JM. Clinical measurement of sit-to-stand performance in people with balance
disorders: validity of data for the Five-Times-Sit-to-Stand Test. Phys Ther.
2005;85(10):1034-45.). Total knee arthroplasty (TKA) is a highly
and increasingly prevalent surgery (66. HCUP Facts and Figures: Statistics on Hospital-Based Care in the
United States [Internet]. Available from:
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)
recommended to those with knee OA showing radiographic evidence of joint damage,
moderate to severe persistent pain and clinically significant functional limitations
that diminish quality of life (77. Panel NIHC. NIH Consensus Statement on total knee replacement
December 8-10, 2003. J Bone Joint Surg Am.
2004;86-A(6):1328-35.). Although
TKA results in reduced pain and improved perceived function (88. Meier W, Mizner R, Marcus R, Dibble L, Peters C, Lastayo PC.
Total knee arthroplasty: Muscle impairments, functional limitations, and
recommended rehabilitation approaches. J Orthop Sports Phys Ther.
2008;38(5):246-56, http://dx.doi.org/10.2519/jospt.2008.2715.
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), patients continue to exhibit reduced voluntary muscle
activation, muscle strength and functional performance even years after surgery
(88. Meier W, Mizner R, Marcus R, Dibble L, Peters C, Lastayo PC.
Total knee arthroplasty: Muscle impairments, functional limitations, and
recommended rehabilitation approaches. J Orthop Sports Phys Ther.
2008;38(5):246-56, http://dx.doi.org/10.2519/jospt.2008.2715.
http://dx.doi.org/10.2519/jospt.2008.271...
). Quadriceps muscle strength deficits
following TKA have considerable long-term consequences associated with impairments
in functional activities (i.e., walking and stair climbing) and lower-limb loading
distribution (88. Meier W, Mizner R, Marcus R, Dibble L, Peters C, Lastayo PC.
Total knee arthroplasty: Muscle impairments, functional limitations, and
recommended rehabilitation approaches. J Orthop Sports Phys Ther.
2008;38(5):246-56, http://dx.doi.org/10.2519/jospt.2008.2715.
http://dx.doi.org/10.2519/jospt.2008.271...
,99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
), as well as the progression of OA in the uninvolved leg
(99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
,1010. Shakoor N, Block JA, Shott S, Case JP. Nonrandom evolution of
end-stage osteoarthritis of the lower limbs. Arthritis Rheum.
2002;46(12):3185-9, http://dx.doi.org/10.1002/art.10649.
http://dx.doi.org/10.1002/art.10649...
).
Resistance training is the most effective exercise for improving muscle strength
(1111. American College of Sports M, Chodzko-Zajko WJ, Proctor DN,
Fiatarone Singh MA, Minson CT, Nigg CR, et al. American College of Sports
Medicine position stand. Exercise and physical activity for older adults. Med
Sci Sports Exerc. 2009;41(7):1510-30,
http://dx.doi.org/10.1249/MSS.0b013e3181a0c95c.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). The ability to improve muscle
strength through resistance training is not affected by the aging process, with both
older men and women without physical limitations showing muscle strength improvement
and training intensity progression similar to young subjects (1212. Ciolac EG, Garcez-Leme LE, Greve JM. Resistance exercise
intensity progression in older men. Int J Sports Med.
2010;31(6):433-8.,1313. Ciolac EG, Brech GC, Greve JM. Age does not affect exercise
intensity progression among women. Journal of strength and conditioning
research. J Strength Cond Res. 2010;24(11):3023-31,
http://dx.doi.org/10.1519/JSC.0b013e3181d09ef6.
http://dx.doi.org/10.1519/JSC.0b013e3181...
). When applied to
older subjects with TKA without OA in the contralateral lower extremity, resistance
training reduces muscle strength deficits and improves function (44. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
Reversing Muscle and Mobility Deficits 1 to 4 Years after TKA: A Pilot Study.
Clin Orthop Relat Res. 2009;467(6):1493-500,
http://dx.doi.org/10.1007/s11999-009-0801-2.
http://dx.doi.org/10.1007/s11999-009-080...
,1414. Petterson SC, Mizner RL, Stevens JE, Raisis L, Bodenstab A,
Newcomb W, et al. Improved Function From Progressive Strengthening Interventions
After Total Knee Arthroplasty: A Randomized Clinical Trial With an Imbedded
Prospective Cohort. Arthritis Rheum. 2009 15;61(2):174-83,
http://dx.doi.org/10.1002/art.24167.
http://dx.doi.org/10.1002/art.24167...
,1515. Petterson SC, Barrance P, Marmon AR, Handling T, Buchanan TS,
Snyder-Mackler L. Time course of quad strength, area, and activation after knee
arthroplasty and strength training. Med Sci Sports Exerc. 2011;43(2):225-31,
http://dx.doi.org/10.1249/MSS.0b013e3181eb639a.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). However, little is known
about the effects of resistance training in older subjects with TKA and symptomatic
OA in the contralateral knee.
Previously reported data from this study showed that 13 weeks of a twice-weekly
resistance training program partially restored muscle strength in older women with
TKA and symptomatic OA in the contralateral knee (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). In this study, the women with TKA and symptomatic OA in the
contralateral knee displayed a relative muscle strength increase and resistance
exercise intensity progression greater than those of young and older healthy women
following the same exercise training program (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). To the best of our knowledge, there is no study analyzing the
effects of resistance training on several muscle strength-related impairments
commonly found in this population, including functional performance, lower-limb
loading distribution and balance.
Increased understanding of the effects of resistance training on the above-mentioned muscle strength-related impairments in subjects with TKA and symptomatic OA in the contralateral knee may help design future therapeutic programs to reduce functional limitations and improve quality of life in this population. Thus, the purpose of the present study was to analyze the effects of a resistance training program on functional capacity, lower-limb loading distribution and balance in older women with TKA and symptomatic OA in the contralateral knee and to compare this group with older and young women without musculoskeletal diseases who performed the same resistance exercise program.
METHODS
Population and study design
A detailed description of the study design, subjects' characteristics and
inclusion/exclusion criteria has been previously published (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). In brief, 7 older women with
unilateral TKA for at least 14 months (38.5±18.5 months; range, 14-66
months) due to severe OA and an established diagnosis of knee OA (1717. Altman R, Asch E, Bloch D, Bole G, Borenstein D, Brandt K, et
al. Development of criteria for the classification and reporting of
osteoarthritis. Classification of osteoarthritis of the knee. Diagnostic and
Therapeutic Criteria Committee of the American Rheumatism Association. Arthritis
Rheum. 1986;29(8):1039-49,
http://dx.doi.org/10.1002/art.1780290816.
http://dx.doi.org/10.1002/art.1780290816...
) in the contralateral limb
(Kellgren/Lawrence scale grades (1818. Ravaud P, Dougados M. Radiographic assessment in osteoarthritis.
J Rheumatol. 1997;24(4):786-91.) of
2-4) (older knee OA and TKA group; OKG), 8 older women without symptomatic
musculoskeletal disorders (older control group; OG) and 8 healthy young women
(young control group; YG) were recruited from the waiting list of the
Cardiovascular and Muscular Fitness Program of the Laboratory of Kinesiology at
the Institute of Orthopedics and Traumatology, School of Medicine, University of
São Paulo. All volunteers were physically inactive and did not practice
resistance training for at least the 12 months preceding the study. The absence
of symptomatic musculoskeletal disorders in the OG and YG was assessed during a
pre-participation structured interview, according to medical records and after
performing clinical evaluations. In these groups, there was no pain during
palpation or active movement, no limitation of more than 10% on range of motion
during the active movement of large joints (knee, hip, shoulders, trunk, elbow,
ankle and wrist), preserved ability to walk fast (30 m) without pain, absence of
musculoskeletal disease according to medical records and no pain and/or
limitations during the past 10 weeks. All OKG and OG volunteers had controlled
hypertension; three OKG volunteers and two OG volunteers had osteopenia; and one
OKG volunteer and two OG volunteers had dyslipidemia (simvastatin,
n = 3). None of the YG women had any chronic conditions or were
taking any medications. The demographic characteristics of the women included in
the study are summarized in Table 1.
All volunteers had their balance, lower-limb loading distribution and functional
capacity (sit-to-stand, rising from the floor, stair-climbing tests and 6-minute
walking (6 MW)) assessed and compared before and after participation in the
13-week resistance training program. All measurements were performed in the
sequence reported above, both before and after the exercise intervention, by the
same technician who was blinded to the research protocol and subject grouping.
Muscle strength and exercise intensity progression were also measured and
compared between groups and these data were previously published (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). The resistance training program
consisted of lower-limb resistance exercises performed twice-weekly. The present
study was approved by the Ethics Committee for Analysis of Research Projects of
Hospital das Clínicas da Faculdade de Medicina da Universidade de São
Paulo (# CAPPesq 447/06). All volunteers read a detailed description of the
protocol and provided their written informed consent.
Balance and lower-limb loading distribution
Balance function and lower-limb loading distribution were assessed before and after the exercise program (4 days after last exercise session) using a Balance Master¯ System version 8.1 (NeuroCom International Inc, Clackamas, OR). This system consists of two force plates resting on force transducers that record vertical ground reaction forces and subsequently calculate the center of pressure, sway angles and movement directions. The balance assessment consisted of four tests, including three static and one dynamic test. In the static tests, the center of gravity sway (degrees per second) was measured during three balance tasks on the force plate system, which were performed with the subjects looking straight ahead while barefoot and standing still. The tasks included bilateral stance for 10 s on a firm surface with the eyes open (test 1), bilateral stance for 10 s on a high-density foam block (15-cm closed-cell) with the eyes open (test 2) and unilateral stance (firm surface) on the right and left leg for 10 s with the eyes open (test 3). If loss of balance resulting in a fall (non-tested foot touching the ground) occurred before ending test 3, the test was validated and the center of gravidity sway was recorded as 12 deg/sec, according to the Balance Master¯ System manual recommendation. Because the 12 deg/sec assumption in case of fall is a recommendation of the manufacturer that may not represent the actual center of gravity sway, the average unilateral stance time was compared before and after training when the fall occurred. During tests 1 and 2, subjects were asked to keep their feet at shoulder width, with their knees extended and arms relaxed along the body. During test 3, subjects were asked to keep the non-tested leg in a position of 0° of hip flexion and 90° of knee flexion and their arms along the body.
Dynamic balance and lower-limb loading distribution were measured during the sit-to-stand test (test 4) with the subjects barefoot. In this test, subjects were asked to rise quickly from a seated to a standing position, during which data were analyzed on weight transfer (time of center of gravity moving from sitting to standing position), rising index (percentage of body weight exerted to rise), end sway (center of gravity movement immediately after standing) and the right/left lower-limb loading symmetry (in percentage) from the sitting to standing position. All subjects performed 3 repetitions of each test and the average was used for data analysis.
Functional performance
Measures of functional performance included the sit-to-stand, rising from the floor, stair climbing and 6 MW tests. All tests were performed the same day (between 2 and 5 p.m.), before and after the exercise program (4 days after last exercise session), following the sequence described below and with a 3-min rest interval between tests. The sit-to-stand test measured the time taken by subjects to perform 5 repetitions of rising from a standard chair without armrests (seat height of 46 cm) to a full upright position as quickly as possible and without assistance (55. Whitney SL, Wrisley DM, Marchetti GF, Gee MA, Redfern MS, Furman JM. Clinical measurement of sit-to-stand performance in people with balance disorders: validity of data for the Five-Times-Sit-to-Stand Test. Phys Ther. 2005;85(10):1034-45.). The rising from the floor test measured the time taken by subjects to rise from the supine position (arms along the body) to a full upright position 40 cm ahead of its original position as quickly as possible. The test was performed 3 times (1 min of rest between tries) and the average was used for analysis. The stair climbing test measured as the time taken by subjects to ascend a flight of 15 steps (15 cm high and 30 cm depth) as quickly as possible. The 6 MW test measured the distance covered in 6 min while walking on a programmable treadmill without inclination and with self-controlled velocity, where the subjects were instructed to walk according to Borg's scale, in exertion levels ranging from light to somewhat hard (from 11 to 13) (1919. Borg GAV. Psychophysical bases of perceived exertion. Med Sci Sports Exerc. 1982 1982;14(5):377-81.), as previously described (2020. Guimaraes GV, Bellotti G, Bacal F, Mocelin A, Bocchi EA. Can the cardiopulmonary 6-minute walk test reproduce the usual activities of patients with heart failure? Arq Bras Cardiol. 2002;78(6):553-60.).
Resistance training program
The resistance training program was performed twice weekly for 13 weeks and was
designed to develop muscle mass and strength. Each exercise session was
monitored by an exercise specialist and consisted of 5 min of warm-up,
approximately 15 min of resistance exercise and 5 min of cool down. The
resistance exercises were performed unilaterally (both legs were trained) and
consisted of two sets of 8-12 repetitions each performed on the leg press, knee
curl and calf raise using weight lifting machines (Biodelta Inc., São
Paulo, Brazil). The initial workload was set at 60% of the 1-repetition maximum
of the weaker leg, as previously reported (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). The volunteers were encouraged to perform at their maximum
capacity during the sets of 8-12 repetitions prescribed, using proper form and
avoiding the Valsalva maneuver. All subjects were instructed to take a 30- to
60-s rest between sets, which were performed on alternating legs. The exercise
specialist also instructed all participants to perform the correct exercise
movement during each session. To promote sufficient workload and produce
improvements throughout the 13 weeks of training, exercise intensity was
increased by 5-10% whenever the subjects had adapted to the exercise workload
(1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
).
Statistical analyses
All data were reported as the mean ± standard deviation. The statistical program Sigma Stat 3.5 for Windows (Systat Software Inc., Chicago, IL, USA) was used for statistical analysis. The Kolmogorov-Smirnov test was applied to ensure a Gaussian distribution of the data. Differences in the volunteers' characteristics and post-exercise muscle strength improvements were analyzed by one-way analysis of variance (ANOVA). Inter- and intragroup comparisons of the data with a Gaussian distribution (functional performance data) were made using two-way ANOVA (group vs. time) with repeated measurements. Bonferroni post-hoc analysis was used to determine significant data indicated by ANOVA. Inter- and intragroup comparisons of the data with a nonparametric distribution (balance and lower-limb loading data) were made using the Kruskal-Wallis and Wilcoxon signed-rank tests, respectively. Dunn's post-hoc test was used to determine significant data indicated by the Kruskal-Wallis test. Because loss of balance resulting in falling occurred only in the OKG, the paired t test was used to compare average unilateral stance time before and after training in this group. The significance level was set at p<0.05.
Based on exercise training studies similar to ours (1212. Ciolac EG, Garcez-Leme LE, Greve JM. Resistance exercise
intensity progression in older men. Int J Sports Med.
2010;31(6):433-8.,1313. Ciolac EG, Brech GC, Greve JM. Age does not affect exercise
intensity progression among women. Journal of strength and conditioning
research. J Strength Cond Res. 2010;24(11):3023-31,
http://dx.doi.org/10.1519/JSC.0b013e3181d09ef6.
http://dx.doi.org/10.1519/JSC.0b013e3181...
), the sample
size calculation estimated an overall sample of 7 subjects for each age group to
provide a power of 80% to detect a muscle strength change of 20% with a
two-sided alpha of <0.05, as previously indicated (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
).
RESULTS
All subjects completed the 13-week resistance training program. No significant difference between groups was observed in resistance training session compliance (OKG = 89.5±8.4%; OG = 90.2±10.1%; YG = 82.5±12.6%). No injuries, muscle damage or major muscle or joint pain associated with the resistance training program were observed in the three groups during the study period.
Functional performance
Functional performance data are displayed in Table 2. The OKG displayed impaired performance (p<0.05) in the 6 MW, sit-to-stand, rising from the floor and stair climbing tests compared to both the OG and YG at baseline. Baseline performance in the 6 MW, sit-to-stand and rising from the floor tests (but not stair climbing) was also impaired (p<0.05) in the OG when compared to the YG. Resistance training was effective at improving (p<0.01) OKG performance in all functional tests and in improving (p<0.05) OG performance in 6 MW, sit-to-stand and rising from the floor tests. The YG did not show any significant improvement in functional performance during follow-up. Improvements in 6 MW and rising from the floor after resistance training were greater (p<0.01) in the OKG (6 MW = 22.6±11.8%; rising from the floor = 15.5±5.3%) than the YG (6 MW = −1.7±4.8%; rising from the floor = 6.7±4.3%). Post-exercise 6 MW improvement was also greater in the OKG than the OG (13.7±5.8%), but this difference failed to reach statistical significance. With these improvements, the OKG showed post-training 6 MW and sit-to-stand performance similar to the baseline performance of the OG.
Balance and lower-limb loading distribution
Balance and lower-limb loading distribution data are displayed in Table 3. The OKG displayed impairments (p<0.05) in bilateral standing balance on foam surfaces (but not on firm surfaces), unilateral standing balance and rising index in comparison to the OG and YG at baseline. The OKG also showed greater baseline loading distribution deficits than the OG and YG (p<0.05), with greater loading in the TKA than OA leg during the sit-to-stand test. Differences in baseline balance performance were also found between the OG and YG, with the OG showing reduced bilateral standing balance on foam surfaces and unilateral standing balance. The OKG showed improvements in unilateral standing balance (72.2±27.7% and 78.2±30.3% in the TKA and OA leg, respectively), sit-to-stand rising index (12.3±6.1%) and loading distribution (57.6±17.2%) during follow-up (p<0.05). However, bilateral stand balance and sway during sit-to-stand did not change. The OG and YG showed no significant change in balance and loading distribution variables after resistance training. With these results, the OKG restored their unilateral stance balance to levels similar to those observed in the OG, while loading distribution was partially restored. It is imperative to note that the 12 ± 0 deg/sec sway velocity of the OA (right) and TKA (left) leg observed during the pre-training unilateral standing of the OKG occurred because all subjects failed to complete the 3 repetitions of the test without loss of balance, resulting in falling (see methods). However, only 2 OKG subjects failed to complete 1 repetition (but were able to complete the other 2 repetitions) of the unilateral stance test during post-training, which resulted in a significant improvement (p<0.001) in the average unilateral stance time after resistance training (Figure 1). None of the individuals in the OG and YG failed to complete any repetition of the unilateral stance test during both pre- and post-training.
Average unilateral stance time until fall among subjects in the older knee OA and TKA group. OA: osteoarthritis. TKA: total knee arthroplasty. c: different from pre-exercise (p<0.001).
DISCUSSION
To our knowledge, this is the first study focused on analyzing the effects of a
resistance training program on functional performance, lower-limb loading
distribution and balance in older women with TKA and OA in the contralateral knee.
These results were also compared to those of older and younger women without
musculoskeletal diseases who performed the same resistance exercise program. The
Baseline baseline characteristics of the OKG were typical to the population of
individuals with knee OA or TKA, exhibiting impairments in functional performance
and lower-limb loading distribution (22. Felson DT. Clinical practice. Osteoarthritis of the
knee. N Engl J Med. 2006;354(8):841-8.,88. Meier W, Mizner R, Marcus R, Dibble L, Peters C, Lastayo PC.
Total knee arthroplasty: Muscle impairments, functional limitations, and
recommended rehabilitation approaches. J Orthop Sports Phys Ther.
2008;38(5):246-56, http://dx.doi.org/10.2519/jospt.2008.2715.
http://dx.doi.org/10.2519/jospt.2008.271...
,99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
).
The primary finding of the present study was that the resistance training program
was a safe and effective intervention to improve functional performance, lower-limb
loading distribution and balance among OKG women. Moreover, several resistance
training-induced improvements, including those in the 6 MW, rising from the floor,
unilateral stand balance, sit-to-stand rising and loading distribution tests, were
greater in the OKG compared to both the OG and YG. These improvements in the OKG
following resistance training were sufficient to restore the performance in the 6
MW, sit-to-stand and unilateral stand balance tests to levels similar to those
observed in the OG at baseline. In addition, sit-to-stand performance and unilateral
stand balance were also restored to post-training OG and baseline YG levels.
Although there is a paucity of studies analyzing the effects of resistance training
in subjects with both TKA and OA in the contralateral knee, the beneficial effects
of resistance training on functional performance has been shown in the early (1414. Petterson SC, Mizner RL, Stevens JE, Raisis L, Bodenstab A,
Newcomb W, et al. Improved Function From Progressive Strengthening Interventions
After Total Knee Arthroplasty: A Randomized Clinical Trial With an Imbedded
Prospective Cohort. Arthritis Rheum. 2009 15;61(2):174-83,
http://dx.doi.org/10.1002/art.24167.
http://dx.doi.org/10.1002/art.24167...
) and late (44. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
Reversing Muscle and Mobility Deficits 1 to 4 Years after TKA: A Pilot Study.
Clin Orthop Relat Res. 2009;467(6):1493-500,
http://dx.doi.org/10.1007/s11999-009-0801-2.
http://dx.doi.org/10.1007/s11999-009-080...
) rehabilitation phases after TKA, as well as in subjects with only
knee OA (2121. Baker KR, Nelson ME, Felson DT, Layne JE, Sarno R, Roubenoff R.
The efficacy of home based progressive strength training in older adults with
knee osteoarthritis: A randomized controlled trial. J Rheumatol.
2001;28(7):1655-65.,2222. King LK, Birmingham TB, Kean CO, Jones IC, Bryant DM, Giffin JR.
Resistance training for medial compartment knee osteoarthritis and malalignment.
Med Sci Sports Exerc. 2008;40(8):1376-84,
http://dx.doi.org/10.1249/MSS.0b013e31816f1c4a.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). In subjects with unilateral TKA without OA in the contralateral
knee, a lower-limb resistance exercise program beginning 3−4 weeks after
surgery resulted in improvements in stair climbing and 6 MW performance during a
12-month follow-up period that were greater than the improvements observed in
subjects who received a standard rehabilitation program (77. Panel NIHC. NIH Consensus Statement on total knee replacement
December 8-10, 2003. J Bone Joint Surg Am.
2004;86-A(6):1328-35.). A thrice-weekly resistance exercise program performed for
12 weeks by subjects that had unilateral (without symptomatic OA in the
contralateral knee) or bilateral TKA for 1−4 years resulted in ∼8.6%
and ∼16.7% improvement on 6 MW and stair climbing performance, respectively
(44. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
Reversing Muscle and Mobility Deficits 1 to 4 Years after TKA: A Pilot Study.
Clin Orthop Relat Res. 2009;467(6):1493-500,
http://dx.doi.org/10.1007/s11999-009-0801-2.
http://dx.doi.org/10.1007/s11999-009-080...
). Although 6 MW distance did not
change in middle-aged subjects with knee OA after 12 weeks of a thrice-weekly
resistance exercise program (2222. King LK, Birmingham TB, Kean CO, Jones IC, Bryant DM, Giffin JR.
Resistance training for medial compartment knee osteoarthritis and malalignment.
Med Sci Sports Exerc. 2008;40(8):1376-84,
http://dx.doi.org/10.1249/MSS.0b013e31816f1c4a.
http://dx.doi.org/10.1249/MSS.0b013e3181...
), greater
improvements in stair-climbing and sit-to-stand performance in older women with knee
OA were observed after 4 months of a resistance exercise program when compared to a
control group receiving an educational program (2121. Baker KR, Nelson ME, Felson DT, Layne JE, Sarno R, Roubenoff R.
The efficacy of home based progressive strength training in older adults with
knee osteoarthritis: A randomized controlled trial. J Rheumatol.
2001;28(7):1655-65.). In this context, the resistance training-induced improvements on 6
MW, sit-to-stand and stair climbing performance observed in this study are in
accordance with previous studies that evaluated subjects with only TKA or knee
OA.
Several studies have shown that a decline in balance performance is a hallmark of the
aging process (2323. Bohannon RW, Larkin PA, Cook AC, Gear J, Singer J. Decrease in
timed balance test scores with aging. Phys Ther.
1984;64(7):1067-70.
24. Choy NL, Brauer S, Nitz J. Changes in postural stability in
women aged 20 to 80 years. J Gerontol A Biol Sci Med Sci.
2003;58(6):525-30, http://dx.doi.org/10.1093/gerona/58.6.M525.
http://dx.doi.org/10.1093/gerona/58.6.M5...
25. Colledge NR, Cantley P, Peaston I, Brash H, Lewis S, Wilson JA.
Ageing and balance: the measurement of spontaneous sway by posturography.
Gerontology. 1994;40(5):273-8,
http://dx.doi.org/10.1159/000213596.
http://dx.doi.org/10.1159/000213596...
-2626. Hageman PA, Leibowitz JM, Blanke D. Age and gender effects on
postural control measures. Arch Phys Med Rehabil. 1995;76(10):961-5,
http://dx.doi.org/10.1016/S0003-9993(95)80075-1.
http://dx.doi.org/10.1016/S0003-9993(95)...
). For example, decline in unilateral standing stability, a
clinical measure for higher-level balance ability (2323. Bohannon RW, Larkin PA, Cook AC, Gear J, Singer J. Decrease in
timed balance test scores with aging. Phys Ther.
1984;64(7):1067-70.,2727. Newton R. Review of tests of standing balance abilities. Brain
Inj. 1989;3(4):335-43,
http://dx.doi.org/10.3109/02699058909004558.
http://dx.doi.org/10.3109/02699058909004...
), has been demonstrated for
women in their 40 s, with significant decline during each subsequent decade (2424. Choy NL, Brauer S, Nitz J. Changes in postural stability in
women aged 20 to 80 years. J Gerontol A Biol Sci Med Sci.
2003;58(6):525-30, http://dx.doi.org/10.1093/gerona/58.6.M525.
http://dx.doi.org/10.1093/gerona/58.6.M5...
). However, little is known about the balance
performance in subjects with TKA or knee OA. The present study shows that older
women with TKA and OA in the contralateral knee have impaired balance performance
than both young and older healthy women. Although no significant difference between
the OKG and OG was observed in the bilateral standing balance on both firm and foam
surfaces, the OKG displayed greater instability during unilateral standing than both
the YG and OG at baseline. Resistance training was effective at improving unilateral
standing balance in the OKG, resulting in significant ∼72% and ∼78%
reductions in sway when standing on the TKA and OA leg, respectively. It is
important to emphasize that resistance training-induced improvement was sufficient
to restore unilateral standing balance of both the TKA and OA legs to levels similar
to those observed in the OG. As falls are a growing problem with significant
economic, personal and social costs among elderly people (2828. Auron-Gomez M, Michota F. Medical management of hip fracture.
Clin Geriatr Med. 2008;24(4):701-19, ix,
http://dx.doi.org/10.1016/j.cger.2008.07.002.
http://dx.doi.org/10.1016/j.cger.2008.07...
29. Masud T, Morris RO. Epidemiology of falls. Age Ageing. 2001;30
Suppl 4:3-7, http://dx.doi.org/10.1093/ageing/30.suppl_4.3.
http://dx.doi.org/10.1093/ageing/30.supp...
-3030. Tinetti ME, Speechley M, Ginter SF. Risk factors for falls among
elderly persons living in the community. N Engl J Med.
1988;319(26):1701-7.) and the inability
to stand on one leg has been shown to be an important predictor of serious falls in
older individuals (3131. Vellas BJ, Wayne SJ, Romero L, Baumgartner RN, Rubenstein LZ,
Garry PJ. One-leg balance is an important predictor of injurious falls in older
persons. J Am Geriatr Soc. 1997;45(6):735-8.), the resistance
training-induced improvement in unilateral standing balance observed in the OKG may
have important implications in fall prevention and its consequences in this specific
population. Additional longitudinal studies investigating the impact of these
balance improvements on fall risk are needed.
Another important finding of the present study was that women in the OKG displayed
increased TKA leg loading during the bilateral sit-to-stand task. This finding is in
contrast to the reduced TKA leg loading observed during the sit-to-stand task at 3
months after surgery in older subjects without symptomatic OA in the contralateral
limb (99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
). Differences in time from surgery (3
vs. ∼38.5 months) and characteristics of the
contralateral leg (asymptomatic vs. symptomatic OA) in the
populations studied are possible explanations for these discrepant findings (99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
). The resistance training program was also
effective in reducing the deficits on lower-limb loading during the sit-to-stand
task. The deficits between the legs improved from −21.2±4.9% to
−9.3±5.2% loading on the OA leg after the 13-week resistance training.
Because the altered loading distribution during bilateral tasks observed in the
early phase after TKA may have important long-term consequences for OA progression
in the uninvolved leg (99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
,1010. Shakoor N, Block JA, Shott S, Case JP. Nonrandom evolution of
end-stage osteoarthritis of the lower limbs. Arthritis Rheum.
2002;46(12):3185-9, http://dx.doi.org/10.1002/art.10649.
http://dx.doi.org/10.1002/art.10649...
), it appears reasonable to suggest that the
opposite loading pattern observed in the OKG, which would overload joints of the TKA
leg during daily living bilateral support tasks, may also have important long-term
consequences, including reduced implant lifespan and early need for revision surgery
(3232. Carr AJ, Robertsson O, Graves S, Price AJ, Arden NK, Judge A, et
al. Knee replacement. Lancet. 2012;379(9823):1331-40,
http://dx.doi.org/10.1016/S0140-6736(11)60752-6.
http://dx.doi.org/10.1016/S0140-6736(11)...
). In this context, the resistance
training-induced improvement in lower-limb loading may have important clinical
implications.
One probable mechanism that may explain the resistance exercise-induced improvements
in functional performance, balance and lower-limb loading distribution is the
enhancement of muscle strength and endurance. Lower muscle strength, in particular
quadriceps strength, has been advocated as the main contributor to the reduced
functional performance and altered lower-limb loading distribution commonly observed
in older subjects with TKA or knee OA (44. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
Reversing Muscle and Mobility Deficits 1 to 4 Years after TKA: A Pilot Study.
Clin Orthop Relat Res. 2009;467(6):1493-500,
http://dx.doi.org/10.1007/s11999-009-0801-2.
http://dx.doi.org/10.1007/s11999-009-080...
,88. Meier W, Mizner R, Marcus R, Dibble L, Peters C, Lastayo PC.
Total knee arthroplasty: Muscle impairments, functional limitations, and
recommended rehabilitation approaches. J Orthop Sports Phys Ther.
2008;38(5):246-56, http://dx.doi.org/10.2519/jospt.2008.2715.
http://dx.doi.org/10.2519/jospt.2008.271...
,99. Mizner RL, Snyder-Mackler L. Altered loading during walking and
sit-to-stand is affected by quadriceps weakness after total knee arthroplasty.
J Orthop Res. 2005;23(5):1083-90,
http://dx.doi.org/10.1016/j.orthres.2005.01.021.
http://dx.doi.org/10.1016/j.orthres.2005...
,1414. Petterson SC, Mizner RL, Stevens JE, Raisis L, Bodenstab A,
Newcomb W, et al. Improved Function From Progressive Strengthening Interventions
After Total Knee Arthroplasty: A Randomized Clinical Trial With an Imbedded
Prospective Cohort. Arthritis Rheum. 2009 15;61(2):174-83,
http://dx.doi.org/10.1002/art.24167.
http://dx.doi.org/10.1002/art.24167...
,2222. King LK, Birmingham TB, Kean CO, Jones IC, Bryant DM, Giffin JR.
Resistance training for medial compartment knee osteoarthritis and malalignment.
Med Sci Sports Exerc. 2008;40(8):1376-84,
http://dx.doi.org/10.1249/MSS.0b013e31816f1c4a.
http://dx.doi.org/10.1249/MSS.0b013e3181...
,2323. Bohannon RW, Larkin PA, Cook AC, Gear J, Singer J. Decrease in
timed balance test scores with aging. Phys Ther.
1984;64(7):1067-70.,3333. Hurley MV. The role of muscle weakness in the pathogenesis of
osteoarthritis. Rheum Dis Clin North Am. 1999;25(2):283-98, vi,
http://dx.doi.org/10.1016/S0889-857X(05)70068-5.
http://dx.doi.org/10.1016/S0889-857X(05)...
). Although muscle strength
data are not reported in the present manuscript, previously reported data from this
study showed lower baseline muscle strength among OKG women, especially in the OA
leg (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). This previous report also showed
that the OKG demonstrated a greater muscle strength increase after the 13-week
resistance training program. Greater improvements were even observed in the OA leg,
which were enough to restore the OA leg muscle strength levels of the OKG to those
of the OG at baseline, as well as to reduce the muscle strength deficits between
legs (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
). One must argue that knee pain is
another factor common to individuals with knee OA that can influence functional
performance and lower-limb loading (3434. Farquhar S, Snyder-Mackler L. The Chitranjan Ranawat Award: The
nonoperated knee predicts function 3 years after unilateral total knee
arthroplasty. Clin Orthop Relat Res. 2010;468(1):37-44,
http://dx.doi.org/10.1007/s11999-009-0892-9.
http://dx.doi.org/10.1007/s11999-009-089...
,3535. Hurwitz DE, Ryals AR, Block JA, Sharma L, Schnitzer TJ,
Andriacchi TP. Knee pain and joint loading in subjects with osteoarthritis of
the knee. J Orthop Res. 2000;18(4):572-9,
http://dx.doi.org/10.1002/jor.1100180409.
http://dx.doi.org/10.1002/jor.1100180409...
). For example, non-operated knee pain was
the primary contributor to performance on the stair climbing and 6 MW tests in
patients 3 years after TKA (3434. Farquhar S, Snyder-Mackler L. The Chitranjan Ranawat Award: The
nonoperated knee predicts function 3 years after unilateral total knee
arthroplasty. Clin Orthop Relat Res. 2010;468(1):37-44,
http://dx.doi.org/10.1007/s11999-009-0892-9.
http://dx.doi.org/10.1007/s11999-009-089...
). In contrast,
resistance training has led to reduced pain in individuals with knee osteoarthritis
(2121. Baker KR, Nelson ME, Felson DT, Layne JE, Sarno R, Roubenoff R.
The efficacy of home based progressive strength training in older adults with
knee osteoarthritis: A randomized controlled trial. J Rheumatol.
2001;28(7):1655-65.). Therefore, it is possible that the
greater improvement in functional performance and balance, as well as the reduction
in lower-limb loading distribution deficits may have been mediated, at least in
part, by pain reduction in the OA knee of the OKG. However, no pain measures were
performed in the present study to confirm this hypothesis.
Poor functional performance levels have been associated with increasing rates of
disability and daily living dependence (3636. den Ouden ME, Schuurmans MJ, Arts IE, van der Schouw YT.
Association between physical performance characteristics and independence in
activities of daily living in middle-aged and elderly men. Geriatr Gerontol Int.
2013;13(2):274-80,
http://dx.doi.org/10.1111/j.1447-0594.2012.00890.x.
http://dx.doi.org/10.1111/j.1447-0594.20...
,3737. Ostir GV, Markides KS, Black SA, Goodwin JS. Lower body
functioning as a predictor of subsequent disability among older Mexican
Americans. J Gerontol A Biol Sci Med Sci. 1998;53(6):M491-5,
http://dx.doi.org/10.1093/gerona/53A.6.M491.
http://dx.doi.org/10.1093/gerona/53A.6.M...
), as well as a higher risk
for mortality and nursing home admission (3838. Guralnik JM, Simonsick EM, Ferrucci L, Glynn RJ, Berkman LF,
Blazer DG, et al. A Short Physical Performance Battery Assessing Lower-Extremity
Function - Association with Self-Reported Disability and Prediction of Mortality
and Nursing-Home Admission. J Gerontol. 1994;49(2):M85-94,
http://dx.doi.org/10.1093/geronj/49.2.M85.
http://dx.doi.org/10.1093/geronj/49.2.M8...
). For example, older subjects aged 70 to 79 years with the 5-repetition
sit-to-stand time above 12.6 s can be considered to have a lower-than-average
performance (3939. Bohannon RW. Reference values for the five-repetition
sit-to-stand test: a descriptive meta-analysis of data from elders. Percept Mot
Skills. 2006;103(1):215-22.). Older subjects aged 65 to
99 years performing the 5-repetition sit-to-stand test above 13.5 seconds displayed
a greater risk (20% to 420%) of having mobility-related disability after 2 years of
follow-up (3737. Ostir GV, Markides KS, Black SA, Goodwin JS. Lower body
functioning as a predictor of subsequent disability among older Mexican
Americans. J Gerontol A Biol Sci Med Sci. 1998;53(6):M491-5,
http://dx.doi.org/10.1093/gerona/53A.6.M491.
http://dx.doi.org/10.1093/gerona/53A.6.M...
). Although both the OKG and OG
showed baseline sit-to-stand performance below the above-mentioned cut-off points,
the resistance training-induced improvements in functional performance of both the
OKG and OG observed in the present study may have important clinical implications by
helping to reduce the risk of future disability and to increase the number of years
with daily living independence.
It is important to note that the YG failed to demonstrate functional improvements
after the resistance training program, which could be due to insufficient exercise
intensity in this population. The resistance training intensity was sufficient to
promote YG muscle strength increases similar to those observed in the OG (1616. Ciolac EG, Greve JM. Muscle strength and exercise intensity
adaptation to resistance training in older women with knee osteoarthritis and
total knee arthroplasty. Clinics. 2011;66(12):2079-84,
http://dx.doi.org/10.1590/S1807-59322011001200013.
http://dx.doi.org/10.1590/S1807-59322011...
) and to those observed in previous studies
(1212. Ciolac EG, Garcez-Leme LE, Greve JM. Resistance exercise
intensity progression in older men. Int J Sports Med.
2010;31(6):433-8.,1313. Ciolac EG, Brech GC, Greve JM. Age does not affect exercise
intensity progression among women. Journal of strength and conditioning
research. J Strength Cond Res. 2010;24(11):3023-31,
http://dx.doi.org/10.1519/JSC.0b013e3181d09ef6.
http://dx.doi.org/10.1519/JSC.0b013e3181...
), suggesting that the failure of the YG to demonstrate functional
improvements was likely due to a ceiling effect of muscle strength on these
variables.
The results of the present and previous studies suggest that the ceiling effect of
muscle strength on balance performance seems to be even more pronounced. Although
the association between lower-limb muscle strength and balance in older people has
been shown in cross-sectional studies (4040. Brech GC, Alonso AC, Luna NM, Greve JM. Correlation of postural
balance and knee muscle strength in the sit-to-stand test among women with and
without postmenopausal osteoporosis. Osteoporos Int. 2013;24(7):2007-13,
http://dx.doi.org/10.1007/s00198-013-2285-x.
http://dx.doi.org/10.1007/s00198-013-228...
41. Gehlsen GM, Whaley MH. Falls in the elderly: Part II, Balance,
strength, and flexibility. Arch Phys Med Rehabil.
1990;71(10):739-41.-4242. Fujita T, Nakamura S, Ohue M, Fujii Y, Miyauchi A, Takagi Y, et
al. Effect of age on body sway assessed by computerized posturography.
J Bone Miner Metab. 2005;23(2):152-6,
http://dx.doi.org/10.1007/s00774-004-0554-7.
http://dx.doi.org/10.1007/s00774-004-055...
), it appears to be weaker
in older individuals without limitations (4040. Brech GC, Alonso AC, Luna NM, Greve JM. Correlation of postural
balance and knee muscle strength in the sit-to-stand test among women with and
without postmenopausal osteoporosis. Osteoporos Int. 2013;24(7):2007-13,
http://dx.doi.org/10.1007/s00198-013-2285-x.
http://dx.doi.org/10.1007/s00198-013-228...
)
compared to older individuals with limitations (1111. American College of Sports M, Chodzko-Zajko WJ, Proctor DN,
Fiatarone Singh MA, Minson CT, Nigg CR, et al. American College of Sports
Medicine position stand. Exercise and physical activity for older adults. Med
Sci Sports Exerc. 2009;41(7):1510-30,
http://dx.doi.org/10.1249/MSS.0b013e3181a0c95c.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). Previous studies have failed to show any resistance
training-induced improvement in balance performance in older subjects without
limitation (4343. Schlicht J, Camaione DN, Owen SV. Effect of intense strength
training on standing balance, walking speed, and sit-to-stand performance in
older adults. J Gerontol A Biol Sci Med Sci. 2001;56(5):M281-6,
http://dx.doi.org/10.1093/gerona/56.5.M281.
http://dx.doi.org/10.1093/gerona/56.5.M2...
,4444. Buchner DM, Cress ME, de Lateur BJ, Esselman PC, Margherita AJ,
Price R, et al. The effect of strength and endurance training on gait, balance,
fall risk, and health services use in community-living older adults.
J Gerontol A Biol Sci Med Sci. 1997;52(4):M218-24,
http://dx.doi.org/10.1093/gerona/52A.4.M218.
http://dx.doi.org/10.1093/gerona/52A.4.M...
), while older adults identified at the highest risk for fall
were shown to benefit from exercise programs including resistance training (1111. American College of Sports M, Chodzko-Zajko WJ, Proctor DN,
Fiatarone Singh MA, Minson CT, Nigg CR, et al. American College of Sports
Medicine position stand. Exercise and physical activity for older adults. Med
Sci Sports Exerc. 2009;41(7):1510-30,
http://dx.doi.org/10.1249/MSS.0b013e3181a0c95c.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). In this context, it has been proposed that
the beneficial effects of resistance training on balance performance likely occur in
the older population with greater limitations (1111. American College of Sports M, Chodzko-Zajko WJ, Proctor DN,
Fiatarone Singh MA, Minson CT, Nigg CR, et al. American College of Sports
Medicine position stand. Exercise and physical activity for older adults. Med
Sci Sports Exerc. 2009;41(7):1510-30,
http://dx.doi.org/10.1249/MSS.0b013e3181a0c95c.
http://dx.doi.org/10.1249/MSS.0b013e3181...
). Thus, the present resistance training-induced improvement in
balance performance observed in the OKG, but not in the OG and YG, supports this
hypothesis.
The present study has several limitations that must be addressed. First, although the
statistical power of the present sample is adequate, caution must be taken in
generalizing the present results. The small number of women studied may not
represent the greater population of patients with knee OA and TKA. Second, the
present data cannot be generalized to men because our population was composed
strictly of women. Third, the lack of a no-exercise control group must be noted. One
could argue that operated patients (OKG), fearing a new surgery if the exercise
fails, may give more attention to the exercise program and could improve in a second
evaluation even without the proposed exercises. However, previous studies with only
TKA subjects showed no improvement in functional performance in no exercise or
standard physical therapy control groups, suggesting that the fear of a new
operation would not improve these variables (44. LaStayo PC, Meier W, Marcus RL, Mizner R, Dibble L, Peters C.
Reversing Muscle and Mobility Deficits 1 to 4 Years after TKA: A Pilot Study.
Clin Orthop Relat Res. 2009;467(6):1493-500,
http://dx.doi.org/10.1007/s11999-009-0801-2.
http://dx.doi.org/10.1007/s11999-009-080...
,77. Panel NIHC. NIH Consensus Statement on total knee replacement
December 8-10, 2003. J Bone Joint Surg Am.
2004;86-A(6):1328-35.,1414. Petterson SC, Mizner RL, Stevens JE, Raisis L, Bodenstab A,
Newcomb W, et al. Improved Function From Progressive Strengthening Interventions
After Total Knee Arthroplasty: A Randomized Clinical Trial With an Imbedded
Prospective Cohort. Arthritis Rheum. 2009 15;61(2):174-83,
http://dx.doi.org/10.1002/art.24167.
http://dx.doi.org/10.1002/art.24167...
). Moreover, the total or partial restoration of OKG
functional performance, lower-limb loading distribution and balance levels to those
of healthy older women performing the same exercise program reinforces the benefits
of resistance training among older women with TKA and OA in the contralateral knee.
Fourth, the 12 deg/sec assumption in case of falling does not represent the real
value of center of gravity sway during the unilateral stance test; rather, this
value is a recommendation from the manufacturer for research and clinical purposes.
Moreover, the fact that all OKG women failed to complete the 3 repetitions of the
unilateral stance test without loss of balance resulting in falls before training
and that only 2 women failed to complete 1 repetition (but were able to complete the
other 2 repetitions) after training, which resulted in a significant improvement in
average unilateral stance time after training, shows that unilateral stance balance
was improved during follow-up in OKG women. Finally, the follow-up period was rather
short, warranting additional studies with a no-exercise control group; in
particular, long-term follow-up focused on analyzing end points such as radiographic
evaluation of disease progression or second TKA may offer additional compelling
evidence for the validity of the present resistance training program.
In summary, resistance training was an effective and safe intervention to improve functional performance, lower-limb loading distribution and balance in older women with TKA and OA in the contralateral knee. These improvements were greater than those observed in older and younger healthy women performing the same resistance training program, resulting in total or partial restoration of several variables, including 6 MW and sit-to-stand performance, unilateral stand balance and lower-limb loading distribution. Although future studies with a no-exercise control group, larger sample size and longer follow-up period are required to confirm the present findings, this study suggests that resistance training may be an effective method to counteract the impairments in functional performance, balance and lower-limb loading distribution in older women with TKA and OA in the contralateral knee.
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No potential conflict of interest was reported.
Publication Dates
-
Publication in this collection
Jan 2015
History
-
Received
22 Aug 2013 -
Reviewed
12 Sept 2014 -
Accepted
7 Nov 2014