REF-1169 · Popov et al., 2006 · Human Physiology · Paper · PubMed

Does no-relaxation training at 50% of max build muscle?

In 18 active men over 8 weeks: strength +21%, volume +9%, vs +35% and +17% at 80% MVC (difference not significant, 9 per group). Abstract only.

Blimited evidenceMeasured on recreational people

Popov and colleagues at the Institute of Biomedical Problems (IBMP, Moscow) tested the idea that restricting the muscle's blood supply by never relaxing it during a set lets a light load build muscle through a metabolic, hormonal stimulus.

Eighteen young, physically active men trained their leg extensors three times a week for eight weeks: nine at 80% of maximal voluntary contraction (MVC) in the usual way, nine at 50% MVC without relaxation. Total training work in the no-relaxation group was about half (77 ± 5 vs 157 ± 7 kJ).

Both groups gained: maximal strength +35% (80% group) vs +21% (no-relaxation group), muscle volume +17% vs +9%. The authors report the between-group differences as not significant, but with nine per group the trial could not detect a difference of this size, and every point estimate favours the heavy group.

Creatine kinase rose more after heavy training and blood lactate rose more after no-relaxation training. Only the no-relaxation group showed a significant rise in growth hormone, IGF-1 and cortisol, which the authors read as hormone release being triggered by a metabolic rather than a mechanical stimulus.

How this relates to the Russian static-dynamic method: this is the closest peer-reviewed test of the no-relaxation principle at a moderate load, run by the same Moscow school.

The abstract does not give the tempo, the range of motion, the set duration, the number of sets or the rest, so we cannot say how closely it matches the static-dynamic prescription as coaches use it (slow, often partial-range reps with no relaxation, sets of roughly 30-60 s to a strong burn; that description is the base's, not this paper's).

No mitochondrial, capillary or fibre-type outcome is reported in this abstract.

Protocol

Participants: 18 young, physically active men (from the abstract); training status, age and selection not given in the abstract.
Groups: group I, 80% MVC with conventional movement (n = 9); group II, 50% MVC "without relaxation" (n = 9). Allocation method not stated.
Exercise: leg extensor muscles; the exercise (likely knee extension or leg press) is not named in the abstract.
Load: expressed as %MVC (the lab's later summary REF-1170 describes the same comparison as 80-85% vs 50% of 1RM).
Tempo, range, relaxation control, set duration, sets, rest, failure: not stated in the abstract.
Frequency and duration: 3 sessions a week for 8 weeks.
Work: total training load 77 ± 5 kJ (no relaxation) vs 157 ± 7 kJ (80% MVC), significantly lower in the no-relaxation group.
Outcomes: maximal strength, muscle volume, blood creatine kinase, lactate, growth hormone, IGF-1, cortisol.

Key Results

Outcome (8 wk)80% MVC (n = 9)50% MVC, no relaxation (n = 9)Between groups
Total training work157 ± 7 kJ77 ± 5 kJsignificantly lower without relaxation
Maximal strength+35% (significant)+21% (significant)not significant
Muscle volume+17% (significant)+9% (significant)not significant
Blood creatine kinaselarger risesmaller riseheavy > no relaxation
Blood lactatesmaller riselarger riseno relaxation > heavy
Growth hormone, IGF-1, cortisolno significant risesignificant riseonly the no-relaxation group changed
Gain per unit of work (our calculation): the no-relaxation group got about 60% of the strength gain (21/35) and about half the volume gain (9/17) for about half the work (77/157).
Power (our inference): with 9 per group, a non-significant difference of 14 percentage points in strength and 8 in volume is not evidence that the methods are equal.

Mechanisms

Measured: higher blood lactate and lower creatine kinase after no-relaxation training than after heavy training, i.e. more metabolic and less mechanical or damage signal.
Measured: only the no-relaxation group raised circulating growth hormone, IGF-1 and cortisol.
Authors' interpretation: restricted blood supply to the working muscle produces a metabolic stimulus that drives anabolic hormone release, which supports growth at a lower load.
Inference: acute systemic hormone rises are not accepted as a driver of hypertrophy (mechanical tension is the prime candidate, REF-682); the heavy group grew at least as much without the hormone rise, which argues against the hormonal explanation rather than for it. In the Japanese LST work, growth hormone after LST and heavy sessions was similar (REF-1171 cites the group's own separate experiment).

Practical Application

Does no-relaxation training at 50% of max build muscle? In 18 active men over 8 weeks: strength +21%, volume +9%, vs +35% and +17% at 80% MVC (difference not significant, 9 per group). Abstract only.
Use it as a lower-load option, not as an equal swap for heavy work. Point estimates favour heavy training by roughly a factor of two for size, on twice the work.
Do not cite this as evidence that static-dynamic training builds mitochondria or helps endurance. Neither was measured; the hormonal response is not a reason to choose the method (REF-682).
For an endurance athlete's strength goals, the base's default stays heavy, low-repetition work (SYNTH-43, SYNTH-44); that recommendation is the base's synthesis, not this paper's.

Limitations

Read from the English abstract only (OpenAlex record and the Springer page); the paper is closed access and the original is in Russian.
Nine per group; randomisation, blinding, the exercise, tempo, range, sets, rest and proximity to failure are not stated in the abstract.
Strength and volume methods are not described in the abstract; between-group statistics are given only as "nonsignificant".
The cohort very likely overlaps with Netreba 2009 (same institute, 18 men, 9 + 9, 8 weeks, 3 times a week) and is pooled in the lab summary REF-1170; do not count these as independent replications.
Hormones were measured as blood concentrations, which do not show local muscle signalling.
Funding and conflicts of interest: not stated in the abstract.
How this entry was checked and changed
Why this level

(from the abstract) — parallel trial with 9 per group (rubric B: parallel trial <20); randomisation, blinding and the exact exercise prescription are not stated in the abstract; the cohort very likely overlaps with Netreba 2009 and the lab summary REF-1170 (same institute, same design, same n)