Home gym kit lists often include separate machines or attachments for single-joint “isolation” work such as biceps curls and leg curls, alongside multi-joint lifts such as presses, pulldowns and squats. This article summarises the abstracts of four trials and one review that compared multi-joint (MJ) and single-joint (SJ) exercise selection: two trials in untrained young men, one in trained men, one six-month trial in trained women, and a 2017 review. All five papers list the same researcher, Paulo Gentil, as an author, so they are not fully independent. The trials are small. This site’s guides to exercise order in a home workout and to weekly sets cover related programming questions.
Trial one: adding arm exercises, untrained men (2013)
Gentil and colleagues, in Applied Physiology, Nutrition, and Metabolism in 2013, randomised 29 untrained young men to 10 weeks of multi-joint exercises only (lat pulldown and bench press) or the same exercises plus elbow flexion and extension. Elbow flexor muscle thickness rose 6.5% in the MJ group and 7.04% in the MJ+SJ group, and peak torque rose 10.40% and 12.85%, with no significant difference between groups. The authors concluded that adding single-joint exercises gave no additional benefit in muscle size or strength in untrained young men.
Trial two: one exercise or the other (2015)
Gentil, Soares and Bottaro, in the Asian Journal of Sports Medicine in 2015, split 29 untrained young men into two groups for 10 weeks, twice a week. One group trained the elbow flexors only with lat pulldowns (multi-joint) and the other only with biceps curls (single-joint). Muscle thickness increased by 6.10% and 5.83% and peak torque by 10.40% and 11.87%, with no difference between groups. The authors suggested the choice between the two types should rest on practical matters such as equipment availability, movement specificity, preference and time.
Trial three: trained men (2015)
De Franca and colleagues, in Applied Physiology, Nutrition, and Metabolism in 2015, studied 20 men with at least two years of resistance training experience, randomised to eight weeks of multi-joint exercises alone or multi-joint plus single-joint exercises. Both groups increased elbow flexion and extension strength and arm size measures, and the comparison between groups showed no significant difference in any variable. The authors concluded that adding single-joint exercises did not seem to give additional benefits to trained men and suggested multi-joint-only training as a time-efficient approach.
Trial four: trained women over six months (2021)
Barbalho and colleagues, in the International Journal of Sports Medicine in 2021, divided 30 trained women into groups doing multi-joint exercises only, single-joint exercises only, or both, for six months. All groups gained strength and muscle thickness. However, the multi-joint and combined groups gained more in the multi-joint lifts than the single-joint group, and had greater increases in muscle thickness in the gluteus maximus, quadriceps and pectoralis major. The single-joint group gained more on the leg curl. The authors concluded that multi-joint exercises seem necessary for optimal results, while single-joint work might be needed for optimal knee flexion strength.
The 2017 review
Gentil, Fisher and Steele, in Sports Medicine in 2017, reviewed 23 experimental studies. For the upper and lower limbs, muscle activity of the prime movers did not differ between SJ and MJ exercises. Long-term studies in the upper limbs found no difference in muscle size or strength gains and no additional effect from including SJ exercises in an MJ programme. The authors concluded that people may not need SJ exercises to obtain equivalent results in activation, hypertrophy and strength, and noted that time is a frequently cited barrier to exercise.
What this means for equipment
- For the upper body, the trials found similar arm gains with and without added curls and extensions, in both untrained and trained men, over 8 to 10 weeks.
- The one longer trial, in trained women, found multi-joint training produced larger increases in muscle thickness in some large muscle groups than single-joint work alone, while leg curl strength favoured single-joint training.
- The samples were small and all five papers share an author, so the findings are suggestive. For most lifts a cable stack or leg curl machine is a convenience rather than a requirement, although leg curl strength favoured single-joint training.
This site’s guide to cable machines and functional trainers covers what that equipment adds.
FAQs
Are curls and triceps extensions necessary if presses and pulldowns are done?
In the 2013 and 2015 trials in men, adding them did not produce significantly greater arm gains over 8 to 10 weeks, although the samples were small.
Do single-joint exercises have any advantage?
In the trial of trained women, the single-joint group gained more on the leg curl, and the 2017 review noted that studies of the lumbar extensors tended to support single-joint work.
The bottom line
Four small trials and a review found that adding single-joint exercises to multi-joint programmes gave similar arm strength and size gains in men over 8 to 10 weeks, and that multi-joint work gave larger muscle thickness gains in some large muscle groups in a six-month trial in women. Single-joint training was linked to better leg curl strength. Because all five papers share an author and the samples are small, the evidence is suggestive rather than settled; it points towards building a programme around multi-joint lifts first and treating isolation equipment as optional, with the exception of leg curl strength, which favoured single-joint training.
Sources
- Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects, Applied Physiology, Nutrition, and Metabolism, 2013 (pubmed.ncbi.nlm.nih.gov)
- Single vs. Multi-Joint Resistance Exercises: Effects on Muscle Strength and Hypertrophy, Asian Journal of Sports Medicine, 2015 (pubmed.ncbi.nlm.nih.gov)
- The effects of adding single-joint exercises to a multi-joint exercise resistance training program on upper body muscle strength and size in trained men, Applied Physiology, Nutrition, and Metabolism, 2015 (pubmed.ncbi.nlm.nih.gov)
- The Effects of Resistance Exercise Selection on Muscle Size and Strength in Trained Women, International Journal of Sports Medicine, 2021 (pubmed.ncbi.nlm.nih.gov)
- A Review of the Acute Effects and Long-Term Adaptations of Single- and Multi-Joint Exercises during Resistance Training, Sports Medicine, 2017 (pubmed.ncbi.nlm.nih.gov)