Training: De minimaal effectieve dosis krachttraining

Meta-analysis of 5 of 6 studies in resistance-trained men found that a single set of 6 to 12 reps at roughly 70 to 85% of a one-rep maximum, performed 2 to 3 times a week with high effort for 8 to 12 weeks, produced a pooled 1RM increase of 26.7 lb (12.09 kg) (95% CI 8.16 to 16.03), made up of 38.5 lb (17.48 kg) on the squat and 18.2 lb (8.25 kg) on the bench press. The base is small, the participants already trained, and the authors describe the gains as the minimum, not the goal. There is no data for the deadlift, and none in trained women or highly trained athletes, so a woman using this protocol is applying a number produced entirely in men.

Using hierarchical random-effects meta-regression across 14 studies (30 treatment groups, 92 effect sizes), 2 to 3 sets per exercise were associated with 46% greater strength gains than a single set (effect-size difference 0.25, 95% CI 0.14 to 0.37, p = 0.0001), in both trained and untrained subjects. There was no significant difference between 1 set and 4 to 6 sets (difference 0.35, 95% CI -0.05 to 0.74, p = 0.17), nor between 2 to 3 and 4 to 6 sets. These are effect sizes, not measured kilograms, the 1-versus-4-to-6-set comparison rested on fewer studies, and the pooled sex composition is not reported.

Across 8 studies (19 treatment groups, 55 effect sizes), multiple sets produced 40% greater hypertrophy effect sizes than a single set (difference 0.10, 95% CI 0.02 to 0.19, p = 0.016), with a stepwise rise in effect size for set number (0.24 for 1 set, 0.34 for 2 to 3, 0.44 for 4 to 6). The individual steps were trends that reached significance only on permutation testing, the base is 8 studies, and the outputs are effect sizes, not measured size. Read against the strength meta-regression from the same author, size is the adaptation that keeps improving with added volume after strength has mostly leveled off.

Across 9 studies (61 treatment groups) in novice and intermediate male trainees, a low weekly set count produced a large pre-to-post strength gain (effect size 0.82, 95% CI 0.47 to 1.17), while higher weekly volume added a modest amount on top (between-group effect-size difference 0.18, 95% CI 0.06 to 0.30 for high versus low, and 0.15 for medium versus low). The authors present this as a graded dose-response, so more sets do help, but the gain from a low weekly volume was already substantial. The outputs are effect sizes not kilograms, and every study was in men.

Across 22 studies, strength effect sizes increased with frequency (0.74, 0.82, 0.93 and 1.08 for 1, 2, 3 and 4+ weekly sessions), but a subgroup analysis of volume-equated studies showed no significant effect of frequency (p = 0.421). The authors conclude the frequency signal is primarily driven by the extra volume that more sessions allow. Subgroups differed: a significant effect appeared in young adults and in women but not in older adults or in men, and for upper-body but not lower-body strength. The subgroups are small, so once weekly volume is set, splitting it across more days adds little on its own.

Across 15 studies, all in young adults, training to failure showed no strength advantage over non-failure training (effect size -0.09, 95% CI -0.22 to 0.05) and no significant hypertrophy advantage (0.22, 95% CI -0.11 to 0.55). In studies that did not equate volume, non-failure training significantly favored strength (-0.32, 95% CI -0.57 to -0.07), and only in the resistance-trained subgroup did training to failure show a small hypertrophy edge (0.15, 95% CI 0.03 to 0.26). The sample is entirely young adults, effort still has to be high, and the authors note that failure training was not detrimental either.

A meta-analysis of 140 studies (1,433 effect sizes) found that strength gains maxed out at a mean training intensity of 60% of a one-rep maximum in untrained people and 80% in trained people, with maximal gains at 3 sessions a week for untrained and 2 for trained, and at 4 sets per muscle group. The paper is from 2003, it identifies the peak of the dose-response, not the minimum, and its 4-sets figure is the optimum for maximal gains. It supports the idea that a challenging load, not gym hours, is what moves strength, and that the frequency where gains level off is low.

In a randomized trial of 100 frail nursing-home residents (63 women, 37 men; mean age 87.1, range 72 to 98), ten weeks of progressive resistance training three times a week raised muscle strength 113% against 3% in the non-exercising groups, gait speed 11.8% against a 1.0% decline, and stair-climbing power 28.4% against 3.6%, while multinutrient supplementation alone changed no primary outcome. Ten weeks is short and the setting was supervised institutional care, and thigh muscle area rose only 2.7% without reaching significance, so most of this gain is neural, not new tissue.

In a randomized trial of 70 adults, 16 weeks of resistance training 3 days a week was followed by a 32-week phase in which participants either stopped or dropped to one-third or one-ninth of that dose. Both reduced doses preserved the myofiber hypertrophy gained in younger adults (20 to 35) but not in older adults (60 to 75), and the one-third dose added further growth in the young. Strength gained in the first phase was largely retained across the 32 weeks even in those who stopped, with only a slight late reduction, and older adults' strength was well preserved. A narrative review of the maintenance literature puts the practical figure at as little as one weekly session of one set to hold strength, and in younger people muscle size too, for up to 32 weeks provided the relative load stays hard, with older adults needing up to 2 sessions and 2 to 3 sets to hold size.

18 young men (mean age 20) were randomized to push-ups matched to about 40% of their bench-press one-rep maximum or to a 40%-1RM bench press, twice a week for 8 weeks. Both groups gained bench-press 1RM (push-ups 134.7 lb (61.1 kg) to 141.5 lb (64.2 kg); bench press 132.3 lb (60.0 kg) to 143.3 lb (65.0 kg)) and triceps and pectoralis thickness, with no meaningful difference between them, though biceps thickness rose only in the bench-press group. It is a small, short trial at a light load in the upper body only, so it shows bodyweight can match a light external load, not heavy loading, and the legs outgrow bodyweight resistance faster than the upper body does.

Across 16 prospective cohorts of adults 18 and over, muscle-strengthening activity carried 10 to 17% lower risk of all-cause mortality, cardiovascular disease, total cancer and diabetes. For mortality the dose-response was J-shaped, with a maximum risk reduction of about 10 to 20% at roughly 30 to 60 minutes a week and the benefit flattening or bending back above that, while diabetes risk kept falling to 60 minutes a week. The curve rests on only 4 of the 16 cohorts that reported dose detail, all using self-reported weekly minutes, which are least reliable in the highest reporters, so the flattening above an hour is best read as no measured extra benefit, not harm.

Across 11 studies (one randomized trial and ten cohorts, 370,256 people, mean follow-up 8.85 years), resistance training was associated with 21% lower all-cause mortality (hazard ratio 0.79, 95% CI 0.69 to 0.91) on its own and 40% lower (0.60, 95% CI 0.49 to 0.72) combined with aerobic exercise, with a borderline association for lower cardiovascular mortality (0.83, 95% CI 0.67 to 1.03). Ten of the eleven studies were observational, risk of bias was rated low to intermediate, and the combined-exercise group is self-selected, so this is a consistent association, not evidence of cause.

Pooling 38 cohort studies (about 1.9 million participants, 63,087 deaths), higher muscular strength carried a hazard ratio of 0.69 for all-cause mortality, stronger in women (0.60) than men (0.69), and higher lower-limb strength carried a 14% lower risk. Reverse causation dominates, since undiagnosed illness lowers strength before diagnosis and independently raises mortality, and none of the studies asked whether the strong participants had trained, so the finding is that being strong tracks with longer life, not that becoming stronger causes it.

In 7 young men and 8 women trained for 8 weeks, neural factors accounted for the larger share of the initial strength gain, and hypertrophy became the dominant contributor only after the first 3 to 5 weeks. Strength also rose in the untrained opposite arm, the cross-education effect, which points to a nervous-system, not a muscle-size cause. It is fifteen people in a 1979 study using surface EMG, so it charts the time course, not settling the mechanism, and the split cannot be quantified per individual.