Effects of training with free weights versus machines on muscle mass, strength, free testosterone, and free cortisol levels
Abstract
Schwanbeck, SR, Cornish, SM, Barss, T, and Chilibeck, PD. Effects of training with free weights versus machines on muscle mass, strength, free testosterone, and free cortisol levels. J Strength Cond Res 34(7): 1851-1859, 2020-Free weights offer a more unstable training environment, which enhances muscle recruitment, whereas some machines have the advantage of using a "cam" pulley system that better matches strength curves. We compared the effect of training with free weights vs. machines on muscle mass, strength, free testosterone, and free cortisol concentrations. Forty-six subjects (26 women; 22 ± 3 years) were randomized to train using free weights or machines for 8 weeks (with each muscle group trained 2-3/weeks, 3-4 sets of 4-10 repetitions). Muscle thickness and strength were measured at 0 and 8 weeks. Salivary hormone concentrations were assessed before and at the end of workouts at the beginning, midway (4 weeks), and end (8 weeks) of the training intervention. Biceps and quadriceps muscle thickness increased (p < 0.01) with no difference between groups. There was a group × time interaction for machine bench press strength (p = 0.05) with the machine group increasing more than the free-weight group (13.9 vs. 8.6%). Free-weight bench press and squat, and Smith machine squat strength increased in both groups (11-19%; p < 0.01) with no difference between groups. Men in the free-weight group had a greater increase in free testosterone from before to after acute training sessions than men in the machine group and all women (p < 0.01); however, there was no differences between groups in free cortisol response to acute resistance exercise. Training sessions with free weights induced greater increases in free testosterone in men; however, training with free weights or machines resulted in similar increases in muscle mass and strength.
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When effort is matched, multi-joint and single-joint exercises, machine-based and free-weight movements promote similar localized hypertrophic adaptations.
“the general literature demonstrates that when effort is matched, these modalities promote similar localized hypertrophic adaptations [153,154].”
From Ribosome Biogenesis as a Putative Bottleneck to Skeletal Muscle Hypertrophy: Mechanisms, Human Evidence, and Practical Modulators (2026) · cites this paper as [154]
An increase in bioavailable testosterone over time seems to induce a greater increase in muscle mass and strength, although this finding has been recently disputed.
“An increase in bioavailable testosterone over time seems to induce a greater increase in muscle mass and strength [60], although this finding has been recently disputed [61].”
From Integrating Transwomen and Female Athletes with Differences of Sex Development (DSD) into Elite Competition: The FIMS 2021 Consensus Statement (2021) · cites this paper as [61]
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“However, the general literature demonstrates that when effort is matched, these modalities promote similar localized hypertrophic adaptations [153,154].”
- Authors
- Schwanbeck, S. R., Cornish, S. M., Barss, T., & Chilibeck, P. D.
- Affiliations
- University of Saskatchewan (CA)
- University of Manitoba (CA)
- University of Alberta (CA)
- Corresponding author
- Chilibeck, Philip D.
- Venue
- Journal of Strength and Conditioning Research
- Published
- 2020-04-30
- Volume
- 34
- Issue
- 7
- Pages
- 1851-1859
- ISSN
- 1064-8011 (ISSN-L)
- OpenAlex
- W3022108872
- Cited by
- 64
- References
- 32
- Citations by year
- 2026: 7 · 2025: 15 · 2024: 8 · 2023: 18 · 2022: 5 · 2021: 9 · 2020: 2
- FWCI
- 8.49
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- The Journal of Strength and Conditioning Research (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
- Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
- Keywords
- free weights, muscle mass, muscle strength, free testosterone, free cortisol, acute hormonal response, sex differences, muscle thickness, bench press, squatting, Smith machine, salivary biomarkers
- MeSH terms
- Adult, Arm, Female, Humans, Hydrocortisone, Male, Random Allocation, Saliva, Testosterone, Exercise, Quadriceps Muscle, Muscle Strength, Resistance Training, Young Adult
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