SUMMARY OF COMPOUND VS ISOLATION EXERCISES FOR HYPERTROPHY : There was no difference in whole-body muscle growth for isolation vs. compound exercises. Regional muscle growth was better with isolation movements. The researchers suggested that strength training with a combination of single and compound lifts can result in greater complete muscle development.
SUMMARY OF COMPOUND VS ISOLATION EXERCISES FOR HYPERTROPHY
- There was no difference in whole-body muscle growth for isolation vs. compound exercises.
- Regional muscle growth was better with isolation movements.
- The researchers suggested that strength training with a combination of single and compound lifts can result in greater complete muscle development.
If you were to ask any bodybuilder if a compound exercise is superior to isolation exercises for muscle growth, they would say, “Of Course They Are!” The benefits of compound exercises are that they recruit many muscle groups.
COMPOUND EXERCISES VS ISOLATION EXERCISES
For decades, people believed that the best way to gain muscle was to do basic whole-body workouts. These workouts focus on multi-joint, compound exercises. The compound exercise list includes pushing exercises like bench presses, squats, bent-over rows, and military presses and pulling exercises like deadlifts, bent-over rows, etc.
Compound exercises recruit multiple muscle groups. For example, an upper body exercise like the bench press recruits the chest, anterior deltoid, and triceps. An isolation exercise like the pec deck fly works the chest and anterior deltoids.
Compound exercises are highly effective for gaining muscle, but many bodybuilders and lifters view isolation exercises as less important than compound exercises. Isolation exercises are just as important for muscle hypertrophy as multi-joint exercises.
Single-joint exercises that isolate a muscle contraction, allowing greater muscle form, isolation, and exercise technique. Isolation exercises can be especially important when a muscle is injured. For example, a quad injury on one leg. A recently previously on Evidence Based Muscle, the squat is highly ineffective for hamstring growth, but hamstring curls are highly effective.
A lifter would use leg extension on the injured leg to enhance muscle growth of the injured leg. The isolation exercise list includes leg extension, triceps extension, biceps curl, cable flyes, and pec deck.
ARE COMPOUND EXERCISES BETTER THAN ISOLATION EXERCISES FOR GAINING MUSCLE?
Some say all you need is multi-joint exercises and that isolation exercises are a waste of time. A 2017 review of the literature (i.e., 23 studies) found that single-joint exercises were unnecessary to maximize size and were only beneficial for correcting muscle imbalances. (Gentil et al., 2017)
The authors found that multi-joint exercises produced greater muscle growth in leg exercises compared to single-joint exercises (i.e., squats result in greater muscle growth than leg extensions). However, the two types of exercises in the biceps and triceps had no significant difference in muscle growth. The author suggested that the arms get additional work from training upper body exercises, so isolation exercises may not be necessary.
A later study compared a multi-joint workout (bench press, squats, military press, dips, etc.) to a single-joint exercise alternative workout (pec deck, leg extension, dumbbell lateral raise) with equal volume.
At the end of the study, the multi-joint exercise group had better overall cardiovascular fitness. Muscle growth was also similar between groups; however, there was a greater trend for the multi-joint group to gain muscle while losing fat. (Paoli et al., 2017) Since more muscles are activated during compound exercises, it makes sense that more calories are burned, and greater fat loss occurs.
BENEFITS OF ISOLATION EXERCISES
A new review of the literature published this month in the Journal of Strength and Conditioning Research found similar findings that compound and isolation exercises are equally effective for muscle growth.
The review found that a combination of single-joint and multi-joint exercises resulted in similar muscle growth as multi-joint exercises for whole muscle growth (i.e., whole muscle growth examines the sum of parts of a muscle being measured) when the training volume was similar.
We know that muscles do not grow uniformly based on exercise angles. For example, an isolation exercise like leg extension targets the middle part of the quad. In contrast, squats result in greater muscle growth of the side of the quad (i.e., vastus lateralis). The researchers found that single-joint exercises improved regional muscle growth (i.e., specific muscle areas).
The researchers suggested combining single and multi-joint exercises can result in greater complete muscle development. (Rosa et al., 2023) The researcher concluded, “We conclude that current evidence indicates similar whole muscle hypertrophy between single and multi-joint exercises. There may be added benefit to combining single and multi-joint exercises for targeting individual aspects of a given muscle, although this hypothesis remains understudied.”
COMPOUND OR ISOLATION EXERCISES FIRST?
While compound exercises are important to build muscle, you need compound and isolation exercises for optimal muscle hypertrophy. Compound exercises do not target specific regions of the muscle fiber as isolation exercises.
There is one study comparing compound or isolation exercise order. For example, one study compared triceps growth with the following exercises: Bench press, skull crushers, skull crushers followed by bench press, or bench press, then skull crushers.
Triceps growth was +4.6% with just bench press, but bench press followed by triceps skull crushers resulted in an 11.5% increase in muscle growth in the triceps. Another interesting observation was that the bench press was quite effective at stimulating the growth of the lateral head of the triceps.
The group that trained with skull crushers had more growth of the lateral and medial heads of the triceps. This suggests that single-joint exercises cause regional muscle growth, not stimulated by multi-joint exercises alone. (Brandão et al., 2020)
In another study emphasizing the importance of a combination of single and multi-joint exercise, subjects performed a supinated dumbbell row (multi-joint exercise) with one arm, and the other arm did biceps curls (single-joint exercise). Bicep growth was nearly double in the bicep curl (11.1%) compared to the dumbbell row (5.2%). (Brandão et al., 2020)
A COMBINATION OF COMPOUND AND ISOLATION EXERCISES IS BEST FOR MUSCLE GROWTH.
Increases in muscle growth are responsive to tension. Whether the tension is accomplished by multi-joint, free weights, or single-joint, machine exercise does not seem to make a difference for whole-body muscle growth.
However, we know that muscles do not grow uniformly throughout a muscle. For example, squats do equally stimulate muscle growth along the entire quad. Leg extensions stimulate greater middle regions of the muscle than a squat.
In summary, it’s important to incorporate both multi-joint and single-joint exercises in your workout routine for optimal muscle hypertrophy. Compound exercises target multiple muscle groups, while isolation exercises to target specific muscle groups. Both provide different effects on muscle growth for a well-rounded physique.
REFERENCES
Brandão, L., de Salles Painelli, V., Lasevicius, T., Silva-Batista, C., Brendon, H., Schoenfeld, B. J., Aihara, A. Y., Cardoso, F. N., de Almeida Peres, B., & Teixeira, E. L. (2020). Varying the Order of Combinations of Single- and Multi-Joint Exercises Differentially Affects Resistance Training Adaptations. J Strength Cond Res, 34(5), 1254-1263. https://doi.org/10.1519/jsc.0000000000003550
Gentil, P., Fisher, J., & Steele, J. (2017). A Review of the Acute Effects and Long-Term Adaptations of Single- and Multi-Joint Exercises during Resistance Training. Sports Med, 47(5), 843-855. https://doi.org/10.1007/s40279-016-0627-5
Paoli, A., Gentil, P., Moro, T., Marcolin, G., & Bianco, A. (2017). Resistance Training with Single vs. Multi-joint Exercises at Equal Total Load Volume: Effects on Body Composition, Cardiorespiratory Fitness, and Muscle Strength. Frontiers in Physiology, 8, 1105-1105. https://doi.org/10.3389/fphys.2017.01105
Rosa, A., Vazquez, G., Grgic, J., Balachandran, A. T., Orazem, J., & Schoenfeld, B. J. (2023). Hypertrophic Effects of Single- Versus Multi-Joint Exercise of the Limb Muscles: A Systematic Review and Meta-analysis. Strength & Conditioning Journal, 45(1). https://journals.lww.com/nsca-scj/Fulltext/2023/02000/Hypertrophic_Effects_of_Single__Versus_Multi_Joint.5.aspx
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