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Randomized trialExercise selection
Fifteen men trained each arm on a cable curl with the shoulder either flexed or extended for ten weeks, matched for resistance profile. Muscle thickness and one-rep-max strength rose in both conditions with no significant differences at proximal, mid or distal regions of the biceps brachii or in the brachialis.
How Fibral applies it: Do not add a second elbow-flexion exercise purely to change shoulder angle; matched for resistance profile, the angle did not change the outcome.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Attarieh P, Nunes JP, Khani S, Negahdar S, Goli A, Nazarirad H, Nazarirad S, Mojtahedi S, Nosaka K, Soori R. (2025). Comparison Between Shoulder Flexed and Extended Positions in Elbow Flexion Resistance Training on Regional Hypertrophy and Maximum Strength: Preacher versus Bayesian Cable Curls. View source
Approved content v1 · updated Aug 17, 2026
ObservationalExercise selection
Recreationally trained women performed nine weeks of either inclined biceps curls or preacher curls. Only the preacher curl group grew significantly, at the distal measurement site, and no statistically significant differences appeared between regions when analysed by group or region.
How Fibral applies it: Prefer an exercise whose resistance is highest where the muscle is most stretched, but treat any claim about targeting one region of a muscle as weak.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Zabaleta-Korta A, Fernández-Peña E, Torres-Unda J, Francés M, Zubillaga A, Santos-Concejero J. (2023). Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women. View source
Approved content v1 · updated Aug 17, 2026
Randomized trialExercise selection
Rugby players completed eight weeks of volume-load-matched lower-body training differing only in whether the main exercise was a bilateral back squat or a unilateral step-up. Both groups improved their trained exercise and also showed transfer to the untrained one.
How Fibral applies it: Expect strength built in one exercise to carry to another that uses similar joint movements and muscles, so a substitution does not restart progress.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Appleby BB, Cormack SJ, Newton RU. (2019). Specificity and Transfer of Lower-Body Strength: Influence of Bilateral or Unilateral Lower-Body Resistance Training. View source
Approved content v1 · updated Aug 17, 2026
Meta-analysisExercise selection
A meta-analysis of nine studies found no difference in muscle hypertrophy between unilateral and bilateral resistance training, while bilateral training produced greater bilateral strength and unilateral training greater unilateral strength. The authors describe the strength result as following the principle of specificity.
How Fibral applies it: Choose unilateral or bilateral work by which expression of strength the lifter is training for; for size the two are interchangeable.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Kassiano W, Nunes JP, Costa B, Ribeiro AS, Loenneke JP, Cyrino ES. (2025). Comparison of Muscle Growth and Dynamic Strength Adaptations Induced by Unilateral and Bilateral Resistance Training: A Systematic Review and Meta-analysis. View source
Approved content v1 · updated Aug 17, 2026
ObservationalExercise selection
Resistance-trained men completed eight weeks of identical programming differing only in whether the squat, bench press, prone bench pull and shoulder press used barbells or machines. Strength and cross-sectional area rose similarly in both, with no difference in joint discomfort.
How Fibral applies it: Treat a machine version of a compound lift as an equivalent substitution for a trained lifter, including when joint discomfort is the reason for the swap.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Hernández-Belmonte A, Martínez-Cava A, Buendía-Romero Á, Franco-López F, Pallarés JG. (2023). Free-Weight and Machine-Based Training Are Equally Effective on Strength and Hypertrophy: Challenging a Traditional Myth. View source
Approved content v1 · updated Aug 17, 2026
Meta-analysisExercise selection
A meta-analysis of thirteen studies comparing free-weight and machine-based strength training found strength changes specific to the modality tested, with no differences between modalities in direct comparison for dynamic strength, isometric strength, jump performance or hypertrophy. The authors conclude the choice comes down to individual preference and goals.
How Fibral applies it: Substitute a machine for a free-weight exercise, or the reverse, on availability and preference; only test in the modality the lifter trains.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Haugen ME, Vårvik FT, Larsen S, Haugen AS, van den Tillaar R, Bjørnsen T. (2023). Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance - a systematic review and meta-analysis. View source
Approved content v1 · updated Aug 17, 2026
Expert consensusExercise selection
A position stand on progression models recommends sequencing exercises to preserve exercise intensity, placing large muscle group work before small, multiple-joint before single-joint, and higher-intensity before lower-intensity work.
How Fibral applies it: Where nothing else decides the order, put multi-joint and heavier work before single-joint and lighter work in the same session.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- American College of Sports Medicine. (2009). American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. View source
Approved content v1 · updated Aug 17, 2026
Expert consensusExercise selection
A review of exercise order found that total repetitions, and therefore volume, are greater when an exercise is placed at the beginning of a session regardless of how much muscle mass it involves. The authors recommend ordering exercises by priority of importance to the training goal rather than by muscle group size.
How Fibral applies it: Order a session by what matters most to the goal, not by the large-before-small convention; the first exercise in the session is the one that accumulates the most work.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Simão R, de Salles BF, Figueiredo T, Dias I, Willardson JM. (2012). Exercise order in resistance training. View source
Approved content v1 · updated Aug 17, 2026
Meta-analysisExercise selection
A meta-analysis of eleven exercise-order studies found no overall difference in strength between orders, but strength gains in a given exercise favoured performing that exercise at the start of the session. Hypertrophy was unaffected by order.
How Fibral applies it: Put the lift the lifter most wants to improve first in its session, and order the rest by priority rather than by muscle size.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Nunes JP, Grgic J, Cunha PM, Ribeiro AS, Schoenfeld BJ, de Salles BF, Cyrino ES. (2021). What influence does resistance exercise order have on muscular strength gains and muscle hypertrophy? A systematic review and meta-analysis. View source
Approved content v1 · updated Aug 17, 2026
Expert consensusExercise selection
A narrative review of time-efficient program design concluded that exercise selection should be built from bilateral, multi-joint exercises taken through full dynamic movements, and that a program needs at least one leg-pressing exercise, one upper-body pulling exercise and one upper-body pushing exercise. Whether those are performed with machines or free weights is a matter of goals, availability and preference rather than of effectiveness.
How Fibral applies it: Select exercises by movement coverage: build the program around bilateral multi-joint lifts and make sure it contains at least one leg press pattern, one upper-body pull and one upper-body push before anything else is added. Choose machines or free weights by what the lifter has and prefers.
Limits and applicability
No limitation statement has been published for this note yet. Treat it as a general evidence-informed rule, not an individualized guarantee.
- Iversen VM, Norum M, Schoenfeld BJ, Fimland MS (2021). No Time to Lift? Designing Time-Efficient Training Programs for Strength and Hypertrophy: A Narrative Review View source
Approved content v4 · updated Aug 17, 2026