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: 

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.

Read the full 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 strategy: 

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).

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