Live For Fit: the method and its sources

Volume table: 10-20 hard sets/muscle/week, diminishing returns.

Confirms the dose-response of volume (systematic review).

Bayesian meta-regression (67 studies, 2,058 participants): counting indirect sets FRACTIONALLY (x0.5) predicts better than counting them as 0 or 1. Frequency has no identifiable effect on hypertrophy at equal volume, but it increases STRENGTH (diminishing returns): hence a frequency driven by the goal.

Training frequency and hypertrophy (basis of the split).

At equal volume, NO difference between high and low frequency on hypertrophy (25 studies). Basis of the decision: sessions are grouped with no loss of muscle.

Proximity to failure: 1-3 RIR is enough (RIR per phase).

Proximity to failure and hypertrophy (meta-analysis).

Resting metabolism equation based on lean mass (basis of "Katch-McArdle").

Fallback metabolism equation when body fat is unknown.

Rate of weight loss that preserves lean mass.

Rate of loss + fat at 15-30% of kcal.

Protein 2.3-3.1 g/kg of lean mass in a deficit (about 1.8-2.7 g/kg of body weight at 15% body fat).

Practical ceiling of ~2.4 g/kg of protein.

Bulking surplus 10-20%, gain 0.25-0.5%/week.

RCT of a 5% vs 15% surplus: a surplus that is too big mostly adds fat.

Reference water intakes (~35 ml/kg/day).

Fluid intake during exercise.

Protein & exercise: choice of powder, cap of ~0.55 g/kg/meal.

Nutrient/protein timing.

Creatine monohydrate 3-5 g/day.

Meta-analysis (14 studies, 392 subjects): at equal volume, split vs full-body changes NEITHER strength NOR hypertrophy. L4F therefore groups workouts for READABILITY, without claiming a muscle gain. Caveat: few studies on hypertrophy (k = 4 to 6), so this is absence of evidence of a difference, not evidence of equivalence.

12-week randomized trial, same exercises and same volume: muscle mass +1.9% (full-body) vs +1.7% (split). Supports the neutrality of workout organization.

Counterintuitive: a muscle recovers FASTER from indirect work (a synergist of rowing: back to baseline at 24 h) than from direct work (curl: still -8.4% at 24 h). This is why L4F does NOT space indirect work away from direct work: nothing justifies it. Single study (n=16), and no study has prospectively tested an indirect-to-direct delay.

Hooper index: subjective fatigue questionnaire (1-7 scale).

Subjective measures detect load; thresholds per individual.

Adding cardio does not reduce hypertrophy/strength on average.

Targeted, dose-dependent interference (frequency/intensity; running weighs more than cycling).

Same-day cardio reduces hypertrophy, not strength.

Interference on strength only appears in the SAME session; separate sessions = no effect.

In a deficit: cardio is NOT the best muscle protector (lifting is); easy cardio deepens the deficit. Diet alone is the worst for lean mass.

HIIT and moderate continuous cardio burn as much fat, so the choice is made on interference, not on fat loss.

Regional activation predicts regional growth (triceps).

Hypertrophy is not uniform within a muscle.

Non-uniform growth of the quadriceps.

Review of regional (uneven) hypertrophy.

Exercise selection steers which region grows.

Long vs short muscle length and regionality.

Squat depth: the vasti respond, the rectus femoris barely.

Seated leg curl > lying (stretch-mediated hypertrophy).

Triceps in the overhead position > neutral.

Standing calf raise > seated for the gastrocnemius.

Mechanisms of stretch-mediated hypertrophy.

Range of motion (ROM) and hypertrophy.

Lengthened-position partials >= full ROM (leg extension).

Calves: lengthened partials > full ROM.

Range of motion (ROM) meta-analysis.

Lengthened partials ~ full ROM (multi-site trial).

Static stretching and muscle architecture.

Incline press: upper chest vs front delt.

Incline press leads to more upper-chest thickness.

Shoulder exercises and deltoid portions.

Lateral delt: cable vs dumbbell (lateral raise).

Grip width on the pulldown and lat activation.

Hip thrust > squat for glute max activation.

Glute hypertrophy is comparable with hip thrust vs squat.

Region-dependent activation of the hamstrings.

Number/alignment of the "tabs" is bony, not modifiable.

Biceps: preacher (distal) vs incline (proximal).

RED-S framework: the risk exposure is ENERGY AVAILABILITY, not body fat %. Notes "the absence of a universal threshold" and replaces numeric thresholds with qualitative terms. No body fat % in the text.

Female athlete triad. No body fat figure: the only quantitative value is "most effects appear below 30 kcal/kg of lean mass/day". The 2007 version deliberately moves away from the 1997 body fat % norms.

Forbes' theory revisited: "a higher initial fat mass is associated with a lower contribution of lean mass to both weight gain and weight loss". This is the basis of the "cut first" advice, BUT the paper gives NO threshold or sex-specific value, and its populations (Minnesota, overfeeding, bariatric surgery) did not lift weights.

12-month case study of a natural bodybuilder: body fat 14.8% → 4.5% → 14.6%, testosterone 9.22 → 2.27 → 9.91 ng/mL. Reversible, but strength had not come back after 6 months. A single case: it illustrates, it does not prove.

REFUTES Frisch's historical threshold (17%/22%): amenorrheic runners had the same body fat as menstruating ones (17.7% vs 17.4%, p = 0.91). "These data do not support the idea that low body fat in itself causes amenorrhea."

Female physique athletes: amenorrheic ones did have lower body fat, BUT unrelated to energy availability, bone density or hormones. To be read ALONGSIDE Sanborn 1987: the two sources do not agree, and this is flagged rather than smoothed over.

DXA norms: women's body fat exceeds men's at every age (median at 20-29: 29.9% vs 20.2%). Justifies making the parameters SEX-SPECIFIC. Defines no clinical threshold.

Bayesian regression, lifting + surplus: the models overall did not predict the results (R2 0.18-0.40). PRELIMINARY study: it does not refute Forbes, it does not conclude. Cited for this uncertainty, not as evidence.

THE review dedicated to the question (8 studies, N=241). Concludes that variation should be decided on an ANATOMICAL criterion, and warns: "excessive rotation of different exercises (i.e., high frequency of change) may actually hinder muscular adaptations". This is the source that made L4F reopen its rule.

TRAINED men, equated volume: no difference in hypertrophy or 1RM between varied and fixed exercises (trivial gaps, ES < 0.2). Basis of the finding "rotation brings nothing demonstrated".

Often cited FOR variation. Kept here with its caveats: lightly trained subjects, and the "constant" group did ONLY ONE exercise (squat), which confuses variation with a multi-exercise program. Identical hypertrophy in the 4 groups (+9.5 to +12.2%).

Best-sized trial (n=70): muscle thickness +7.8-17.7% (constant) vs +7.5-19.3% (varied), p > 0.05, no regional difference either. Contradicts the optimistic half of the same authors' 2022 review.

Unilateral design (one arm against the other, n=32): "neither increased volume nor exercise variation, alone or combined, enhanced changes in upper-limb lean tissue mass".

Meta-analysis (35 studies) of periodization AT EQUATED VOLUME. Decisive for what it does NOT cover: it only periodizes volume and intensity, never exercise selection, so "periodization" cannot be invoked to justify a rotation. No hypertrophic benefit (ES 0.13, p = 0.27), small effect on strength (ES 0.31, p = 0.02).

1RM estimation (load reference per phase). Formula, not indexed.

%1RM to reps table (target weight). Book, no DOI.

Body fat estimation (neck/waist/hips).

MEV/MAV/MRV volume landmarks + maintenance dose. Practical framework, not a peer-reviewed article.

Maintaining rather than building: one session a week is enough to keep strength and mass. This is what makes the "my sport first" block (1 session/week) sustainable.

Tapering: lower the VOLUME while keeping intensity and frequency, over about 2 weeks. Parameters of the "I'm peaking" block.

Concurrent training: adding endurance does not reduce hypertrophy or strength on average. Basis of the moderate cut rather than giving up.

Heavy strength improves running economy. Justifies keeping gym work for runners, endurance included.

Exercise programs improve landing quality (LESS score), a knee risk factor. Basis of the knee control work in team sports.

The Nordic hamstring halves hamstring injuries (8,459 athletes). Basis of the hamstring braking work.

Caution, ESSENTIAL NUANCE: a methodological reanalysis judges this evidence INCONCLUSIVE (high bias). We therefore offer this work, and never present it as a guarantee.

Ice hockey: a pre-season adductor strengthening program reduces groin injuries. The number 1 target in hockey, rather than the quadriceps.

Rugby: a strengthening warm-up reduces injuries and concussions in young players. Basis of the neck work in rugby.

Shoulder in overhead sports: rotator strength and scapular control. Caution: SCREENING by range of motion does not work: we strengthen, we do not pretend to screen.

NEVER TO BE CITED AS EVIDENCE: randomized trial on 840 athletes, 64.7% injured in the program group against 65.0% in controls. The authors conclude there was no efficacy, and only 8.8% actually followed the program.

THE MOST IMPORTANT RESULT: with an identical program, the effect ranges from -92% injuries with high adherence to -12% with low adherence. Simple, kept-up content beats rich, abandoned content: this is what justifies the minimum dose.

Tendinopathy: heavy slow loading gives a lasting result equivalent to eccentric work. Basis of the decision to offer light work AROUND a tendon rather than complete rest.

Knee osteoarthritis: exercise reduces pain and improves function, with the effect holding 2 to 6 months after stopping. Basis of the decision to keep moving around a worn joint rather than sidelining it.

4 to 6 g per day for at least 2 to 4 weeks raise muscle carnosine. Clearest effects on efforts of 1 to 4 minutes. Tingling eases by splitting into doses of 1.6 g.

3 to 6 mg per kg of body weight improve strength, endurance and alertness. Beyond that, no additional benefit and more side effects.

Athletes have an increased risk of omega-3 insufficiency. Supplementation with EPA and DHA supports endurance, cardiovascular function, recovery and sleep.

15 g of gelatin enriched with vitamin C, one hour before intermittent exercise, double the collagen synthesis markers compared with placebo. Dose-dependent effect, visible from 4 hours.

The reference dose is 8 g before the effort, but results remain contradictory from one study to the next. The effect, when there is one, is small.

Nutrition makes a small but real contribution to performance, and supplements a minor part of that nutrition. A full nutritional assessment must precede any decision to supplement.

A serum 25-OH vitamin D level above 30 ng/mL is the sufficiency threshold used by most studies. Insufficiency affects 42 to 83% of athletes, especially in winter and indoors.

0.3 g per kg is the optimal dose, 60 to 180 minutes before the effort. Established benefits on intense efforts of 30 seconds to 12 minutes and in combat sports, including boxing.

An intake 2 to 3 hours before the effort, at 6-12 mmol of nitrates, improves physical performance. Beyond 15 mmol, no additional benefit.

A single source of carbs is oxidized at a maximum of 60 g per hour. To reach 90 g per hour in very long events, several transporters must be combined, typically glucose and fructose.

49 trials, 1,863 participants. Supplementation increases strength and lean mass, but the effect plateaus around 1.6 g per kg per day of total intake.

Ergogenic effect confirmed, maximal on efforts of 30 seconds to 10 minutes. Beyond and below this window, the benefit fades.

12 randomized trials. Statistically significant reduction in soreness 48 h after eccentric exercise.

41 randomized trials from 2011 to 2025, more than 1,800 participants. Consistent reduction in inflammatory markers and soreness, provided the dose is sufficient and the intake prolonged.

Falling asleep is about 17 minutes quicker compared with placebo. Total sleep duration is not significantly changed.

19 studies, 768 participants. Favorable effects on lean mass, tendon morphology and maximal strength. 15 g per day for at least 8 weeks is needed.

Improvement in bone remodeling markers and muscle performance, with a clear synergy when collagen is combined with vitamin D and calcium.

Intense, prolonged effort, especially in the heat, increases intestinal permeability. Some strains strengthen the intestinal barrier and reduce the frequency of respiratory infections.

Ferritin rises clearly only in athletes whose starting value is 12 µg/L or lower. Above that, the effect is minimal or null. Effective doses observed: 16 to 100 mg of elemental iron per day.

23 studies, 669 female athletes. Iron deficiency degrades endurance performance by 3 to 4%. Correction in deficient subjects improves performance by 2 to 20%.

19 trials. Recovery of maximal voluntary strength improved at all measurement times, and C-reactive protein lowered up to 48 hours.

14 studies, 349 subjects. Reduction in soreness, creatine kinase and interleukin-6, with a gain in range of motion. An early low-dose intake acts on soreness, an intake right after the effort on blood markers.

The effect depends more on the timing of the intake than on the dose. The heterogeneous results of the literature are largely explained by very variable administration protocols.

Muscle protein synthesis plateaus at ~0.40 g/kg per meal in older adults versus ~0.24 in young people: from age 60, the same total dose must be spread over more doses.

International position: at least 1.0 to 1.2 g/kg/day of protein after 65 (L4F targets are already above that), with attention paid to the dose per meal.

Meta-analysis of 22 randomized trials (721 participants, aged 50-80): creatine + strength training adds ~1.4 kg of lean mass and more strength than strength training alone.

Randomized trial in ages 60-85: 6 months of EPA/DHA increase thigh muscle volume (+3.6%) and strength, and slow age-related loss.

Systematic review: the evidence does NOT show slower recovery with age after a strength session (two studies even find the opposite for soreness).

Meta-analysis of 25 randomized trials (aged 65 and over): strength training remains fully effective on strength and muscle mass in older adults; the optimal dosage exists and can be programmed.

NSCA position: 2 to 3 sessions per week, 2 to 3 sets per exercise, 70 to 85% of 1RM. Firm loads remain recommended with age, without systematically going to failure.

Acute post-session hormone changes (testosterone, GH) predict NEITHER muscle gain NOR strength gains: chasing a session hormone peak is pointless.

Meta-analysis: training does not reliably raise baseline testosterone in aging men. You train for muscle and strength, not for a hormone number.

Review: testosterone drops by about 1 to 2% per year with age; the effect of exercise on it depends on type, intensity and volume, and remains modest.

One week at 5 h of sleep per night makes testosterone fall by 10 to 15%, even in young, healthy men: sleep is the first hormonal lever, at any age.

Group A: strong evidence, sustained use. Group B: emerging evidence. Group C: no demonstrated benefit. Group D: banned or at high risk of contamination.

Not recommended in case of cardiovascular risk factor, heart disease or kidney or liver impairment. Avoid combining several supplements with each other or with medication. Favor products compliant with the EN 17444 standard.

Authorized claims: contribution to normal muscle function, to normal nervous system function and to the reduction of tiredness and fatigue. Reference intake of 300 to 400 mg per day in adults.

Estimates body fat from neck circumference, waist circumference, hip circumference in women, and height. Validated against hydrostatic weighing.

Adult safety guidelines: up to 400 mg per day and 200 mg per single dose, including before exercise.