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Strength training and aerobic exercise training for muscle disease

Nicoline BM Voet, Elly L van der Kooi, Baziel GM van Engelen, Alexander CH Geurts
Cochrane Neuromuscular Disease Group
nicole.voet@radboudumc.nl
003907
» In the Cochrane Library
06/12/2019

Abstract

Background

Strength training or aerobic exercise programmes, or both, might optimise muscle and cardiorespiratory function and prevent additional disuse atrophy and deconditioning in people with a muscle disease. This is an update of a review first published in 2004 and last updated in 2013. We undertook an update to incorporate new evidence in this active area of research.

Objectives

To assess the effects (benefits and harms) of strength training and aerobic exercise training in people with a muscle disease.

Search methods

We searched Cochrane Neuromuscular’s Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL in November 2018 and clinical trials registries in December 2018.

Selection criteria

Randomised controlled trials (RCTs), quasi‐RCTs or cross‐over RCTs comparing strength or aerobic exercise training, or both lasting at least six weeks, to no training in people with a well‐described muscle disease diagnosis.

Data collection and analysis

We used standard methodological procedures expected by Cochrane.

Main results

We included 14 trials of aerobic exercise, strength training, or both, with an exercise duration of eight to 52 weeks, which included 428 participants with facioscapulohumeral muscular dystrophy (FSHD), dermatomyositis, polymyositis, mitochondrial myopathy, Duchenne muscular dystrophy (DMD), or myotonic dystrophy. Risk of bias was variable, as blinding of participants was not possible, some trials did not blind outcome assessors, and some did not use an intention‐to‐treat analysis.

Strength training compared to no training (3 trials)

For participants with FSHD (35 participants), there was low‐certainty evidence of little or no effect on dynamic strength of elbow flexors (MD 1.2 kgF, 95% CI −0.2 to 2.6), on isometric strength of elbow flexors (MD 0.5 kgF, 95% CI −0.7 to 1.8), and ankle dorsiflexors (MD 0.4 kgF, 95% CI −2.4 to 3.2), and on dynamic strength of ankle dorsiflexors (MD −0.4 kgF, 95% CI −2.3 to 1.4).

For participants with myotonic dystrophy type 1 (35 participants), there was very low‐certainty evidence of a slight improvement in isometric wrist extensor strength (MD 8.0 N, 95% CI 0.7 to 15.3) and of little or no effect on hand grip force (MD 6.0 N, 95% CI −6.7 to 18.7), pinch grip force (MD 1.0 N, 95% CI −3.3 to 5.3) and isometric wrist flexor force (MD 7.0 N, 95% CI −3.4 to 17.4).

Aerobic exercise training compared to no training (5 trials)

For participants with DMD there was very low‐certainty evidence regarding the number of leg revolutions (MD 14.0, 95% CI −89.0 to 117.0; 23 participants) or arm revolutions (MD 34.8, 95% CI −68.2 to 137.8; 23 participants), during an assisted six‐minute cycle test, and very low‐certainty evidence regarding muscle strength (MD 1.7, 95% CI −1.9 to 5.3; 15 participants).

For participants with FSHD, there was low‐certainty evidence of improvement in aerobic capacity (MD 1.1 L/min, 95% CI 0.4 to 1.8, 38 participants) and of little or no effect on knee extension strength (MD 0.1 kg, 95% CI −0.7 to 0.9, 52 participants).

For participants with dermatomyositis and polymyositis (14 participants), there was very low‐certainty evidence regarding aerobic capacity (MD 14.6, 95% CI −1.0 to 30.2).

Combined aerobic exercise and strength training compared to no training (6 trials)

For participants with juvenile dermatomyositis (26 participants) there was low‐certainty evidence of an improvement in knee extensor strength on the right (MD 36.0 N, 95% CI 25.0 to 47.1) and left (MD 17 N 95% CI 0.5 to 33.5), but low‐certainty evidence of little or no effect on maximum force of hip flexors on the right (MD −9.0 N, 95% CI −22.4 to 4.4) or left (MD 6.0 N, 95% CI −6.6 to 18.6). This trial also provided low‐certainty evidence of a slight decrease of aerobic capacity (MD −1.2 min, 95% CI −1.6 to 0.9).

For participants with dermatomyositis and polymyositis (21 participants), we found very low‐certainty evidence for slight increases in muscle strength as measured by dynamic strength of knee extensors on the right (MD 2.5 kg, 95% CI 1.8 to 3.3) and on the left (MD 2.7 kg, 95% CI 2.0 to 3.4) and no clear effect in isometric muscle strength of eight different muscles (MD 1.0, 95% CI −1.1 to 3.1). There was very low‐certainty evidence that there may be an increase in aerobic capacity, as measured with time to exhaustion in an incremental cycle test (17.5 min, 95% CI 8.0 to 27.0) and power performed at VO2 max (maximal oxygen uptake) (18 W, 95% CI 15.0 to 21.0).

For participants with mitochondrial myopathy (18 participants), we found very low‐certainty evidence regarding shoulder muscle (MD −5.0 kg, 95% CI −14.7 to 4.7), pectoralis major muscle (MD 6.4 kg, 95% CI −2.9 to 15.7), and anterior arm muscle strength (MD 7.3 kg, 95% CI −2.9 to 17.5). We found very low‐certainty evidence regarding aerobic capacity, as measured with mean time cycled (MD 23.7 min, 95% CI 2.6 to 44.8) and mean distance cycled until exhaustion (MD 9.7 km, 95% CI 1.5 to 17.9).

One trial in myotonic dystrophy type 1 (35 participants) did not provide data on muscle strength or aerobic capacity following combined training. In this trial, muscle strength deteriorated in one person and one person had worse daytime sleepiness (very low‐certainty evidence).

For participants with FSHD (16 participants), we found very low‐certainty evidence regarding muscle strength, aerobic capacity and VO2 peak; the results were very imprecise.

Most trials reported no adverse events other than muscle soreness or joint complaints (low‐ to very low‐certainty evidence).

Authors’ conclusions

The evidence regarding strength training and aerobic exercise interventions remains uncertain. Evidence suggests that strength training alone may have little or no effect, and that aerobic exercise training alone may lead to a possible improvement in aerobic capacity, but only for participants with FSHD. For combined aerobic exercise and strength training, there may be slight increases in muscle strength and aerobic capacity for people with dermatomyositis and polymyositis, and a slight decrease in aerobic capacity and increase in muscle strength for people with juvenile dermatomyositis. More research with robust methodology and greater numbers of participants is still required.

Plain language summary

Strength training or aerobic exercise training for muscle disease

Review question

What are the effects (benefits and harms) of strength training and aerobic exercise training in people with muscle disease?

Background

Strength training, which is performed to improve muscle strength and muscle endurance, or aerobic exercise programmes, which are designed to improve aerobic (cardiovascular) fitness, might optimise physical fitness and muscle strength in people with muscle disease. The number of training studies in people with muscle diseases is increasing steadily. This is an updated review that includes nine newly added studies.

Study characteristics

The review includes three trials of strength training in people with facioscapulohumeral muscular dystrophy (FSHD) and myotonic dystrophy (136 participants), five trials of aerobic exercise (cardiovascular training) in people with dermatomyositis and polymyositis (14 participants), Duchenne muscular dystrophy (DMD; 30 participants) and FSHD (111 participants), and six trials of strength training combined with aerobic exercise in people with mitochondrial myopathy (18 participants), myotonic dystrophy type I (35 participants), dermatomyositis and polymyositis (68 participants), and FSHD (16 participants).

Key results and certainty of the evidence

The findings of this review should be interpreted with caution due to the variable quality of the included studies, variation in exercise interventions, and outcomes measured. It was not possible for participants to be blinded (unaware of whether or not they were in the exercise group). We have, at best, low confidence in the results because of the small numbers of people included in the studies, a variability in results across studies, differences in populations and interventions across studies, and some issues regarding the conduct and design of the studies, in addition to the lack of blinding.

We have little confidence in findings that strength training has little or no effect on dynamic strength (during movement) of the elbow flexors and ankle dorsiflexors or on isometric (static contraction) strength of elbow flexors and ankle dorsiflexors in people with FSHD; and that the combination of strength training and aerobic exercise may have a positive effect on right and left knee extensor strength but no effect on right and left hip flexor strength in people with juvenile dermatomyositis. (Flexors are muscles that tend to bend the joint and extensors straighten or extend the joint).

We have very little confidence in findings that in people with myotonic dystrophy type 1 there may be a slight improvement in isometric wrist extensor strength and little or no effect on hand grip force, pinch grip force or isometric wrist extensor strength after strength training; that participants with dermatomyositis, polymyositis and juvenile dermatomyositis may experience a positive effect of the combination of strength training and aerobic exercise on dynamic strength of right and left knee extensors; that people with dermatomyositis and polymyositis may have a positive effect of aerobic exercise training on aerobic capacity; and that there may be a slight decrease in aerobic capacity after aerobic exercise training in people with juvenile dermatomyositis.

We found evidence that was too uncertain for conclusions to be drawn regarding the effect of strength training on shoulder muscle strength, pectoralis major muscle strength and anterior arm muscle strength in mitochondrial myopathy, the effect of aerobic exercise training in people with mitochondrial myopathy, in the effect of aerobic exercise training on maximal workload in people with FSHD, and on the number of arm and leg revolutions in a six‐minute cycle test in boys with DMD.

We have limited or very little confidence in findings of the absence of adverse events (side effects) in most studies. Additional high‐quality studies with a high number of participants is needed.

Date up to date

The most recent search for evidence was in November 2018.

Authors’ conclusions

Implications for practice

The evidence regarding strength training and aerobic exercise interventions remains uncertain. Low‐certainty evidence suggests that strength training alone may have little or no effect, and that aerobic exercise training alone may lead to a possible improvement in aerobic capacity, but only for participants with FSHD. For combined aerobic exercise and strength training, very‐low certainty evidence shows that there may be slight increases in muscle strength and aerobic capacity for people with dermatomyositis and polymyositis, and there is low‐certainty evidence for a slight decrease in aerobic capacity and increase in muscle strength for people with juvenile dermatomyositis. The included studies in this review reported no negative side effects of either strength or exercise training in people with a muscle disease. The optimal exercise modality and intensity of exercise for people with a muscle disease is still unclear.

Implications for research

There is a need for more research to establish whether strength training is beneficial in all forms of muscle disease, and whether exercise training is beneficial in Becker muscular dystrophy and inclusion body myositis, and to define the optimal aerobic exercise programmes for people with a muscle disease.Specific diagnostic criteria should be used and reported for all muscle diseases included. Information on the severity of the muscle disease in participants should also be presented so as to allow readers to assess the generalisability of the results to other people with a similar type and severity of muscle disease. In studies with a small sample size, participants should be stratified for disease severity. Another related characteristic that may influence outcome is the level of activity (sedentary versus active) at baseline, because in the healthy population untrained persons respond with higher percentages and rates of gain in strength, compared with trained individuals (Garber 2011). Activity level and change in activity level for each participant should be monitored objectively during the study period, for example with an accelerometer.

When people with different neuromuscular disorders but with similar distribution and severity of muscle weakness participate in the same study, the data should also be presented for each major type of muscle disease separately, to detect possible disease‐specific trends.

In strength training and aerobic exercise intervention studies, the training programme should be described in detail, just as with the prescription of drugs. Study authors should provide information about the type(s) of exercise, the intensity (including progression rate), frequency, duration per exercise session, the duration of the entire programme, as well as the trained muscle groups, and the supervision of training. Studies including well‐described interventions, and more specifically harmonisation of outcome measures across studies, may improve the quality and comparability of the evidence. These studies would ultimately facilitate the development of uniform exercise guidelines for people with muscle diseases. Although some studies measured the same domains, they used different test protocols for strength, aerobic capacity, muscle endurance, fatigue, quality of life and pain, which impeded pooling of data. The large variety in outcome measures that the studies used underscores the need for a general agreement about most important measures to assess effects of exercise intervention. A core set of outcome measures to determine the effect of exercise therapy would enable comparison of the magnitude of effect of different exercise regimens.

In summary, the review authors’ recommendations for future studies are as follows.

  • Participants with different muscle disorders can participate in one study, but data should be presented for each major type of muscle disease separately if possible.
  • Randomised controlled comparisons should be made with participants having the same types of muscle disease. The effect of training in people with a muscle disease should be compared to a non‐exercising control group of people with the same muscle disease and not to healthy individuals or to contralateral non‐exercised limbs.
  • An appropriate placebo intervention is recommended in order to measure exercise‐specific benefits.
  • Stratified randomisation is strongly advised with regard to disease severity, particularly in studies with a small sample size. It should also be considered for pre‐training level of activity (sedentary versus active), particularly in aerobic intervention studies.
  • The following aspects of the training intervention should be specified: type(s) of exercise training, intensity and progression rate, frequency, duration per exercise session and of the entire programme, trained muscle groups, supervision of training, and adherence. Duration of the training intervention should be at least six weeks.
  • Outcomes should at least include measures of muscle function (for example, strength, endurance measured by the maximum duration of contraction) and aerobic capacity (for example, work capacity measured by an incremental cycle test), and functional assessments such as a six‐minute walk test. Researchers should be aware of the specificity of training effects in their choice of outcome measures. The following evaluations are strongly advised: measures of quality of life, pain and experienced fatigue.
  • Outcome measures should be standardised in order to compare study results.
  • Outcomes assessors should be blinded to interventions, to avoid measurement bias.
  • Activity levels of participants in the control group should be monitored objectively in order to assess the specific benefits of aerobic exercise and strength training exercise.
  • A long‐term follow‐up without supervised exercise is recommended in order to measure the proportion of the population that maintains the programme of exercise employed in the intervention, or some other form of exercise.
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