Science
The research the BLOCKS assistant answers from: 1,118 studies and 81 guides, each graded for how strong the evidence is and who it was measured on, with a link to the original paper.
1,118 entries
BFive to seven weeks of sleep extensionA goal of at least 10 h in bed, which bought about 111 min more sleep a night — made 11 collegiate basketball players faster over a timed sprint (16.2 → 15.5 s), more accurate (free throws +9%…Mah 2011C+Training monotony is the week's mean daily load divided by the standard deviation of those daily loads and training strain is the week's load multiplied by monotonyAnd in the 25 athletes the constructs were built on, illness clustered where each athlete crossed a threshold identified for him individually, mostly on strain, not where anyone crossed a shared…Foster 1998C+Five things must be addressed before a runner runs again after a tibial bone stress injuryThen an individualised walk-run return, distance before speed, gated by symptoms rather than a calendar; all resting on level IV evidenceGeorge 2024AThere is now an international consensus on bone stress injuriesAnd its headline number is that a 41-member panel could agree on only 41 of 58 statements, so a confident single answer about grading, screening or return timing is over-claimingHoenig 2025B+Same rider, same watts, same fluid replacement: heart rate drifted 11% and VO2max fell 15% at 35 °C, while at 22 °C it drifted 2% and VO2max did not significantly changeThe environment, not the athlete, wrote most of the numberLafrenz 2008C+Cardiovascular drift begins after about 10 min of prolonged moderate exercise, and the heart-rate rise is not noise: it comes with a genuine fall in maximal oxygen uptake, so the same watts become a harder effortWingo 2012B+In 5069 endurance athletes (abstract; 5311 in the Results and Table 1, corrected 2026-10-12, full text) tested to exhaustion, 9 of 13 age-based HRmax formulas differed significantly from the measured valueAnd even the four that agreed on average were wrong by about 10 bpm on the individual (RMSE 9.1-10.5)Kasiak 2023ANitrate, pooled across 20 meta-analyses: it moves time to exhaustion, muscular endurance, distance covered and peak powerAnd no other performance outcome, time trial and VO2max includedPoon 2025AAn independent 2023 taper meta-analysis reproduces Bosquet's shape: the time trial improves and VO2max and economy do notAnd the effect appears only in the subgroups that KEPT intensity and frequencyWang 2023A-Pooled over 211 heat-acclimation papers, the typical block is 8 ± 4 exposures of 90 ± 36 min and buys a 3.1% time-trial gainAnd adding sessions buys a different adaptation from making sessions longerMcDonald 2025B+The trained-athlete ceiling could move from 90 to 120 g/hAnd the 120-200 g/h now circulating in the field is a practice the authors say the evidence does not yet supportMorton 2026B+Five days of heat acclimation is not enough to raise the critical environmental limitNine are; and the drop in core-temperature rise appears only after 4-8 days of recovery, not during the blockvan den Bogaard 2025A-Do light loads grow slow-twitch fibres more than heavy ones?Not shown: in 8 small biopsy trials type I growth was flat across loads; type II grew a little more with heavy loads, all CIs crossing zero. Mostly untrained.Varovic 2026C+How much do elite ultrarunners eat and spend in a hot 100-miler?One world-class runner: 16,104 kcal spent, ~6,400 eaten in race (86 g carbs/h), no distress reported, −4.3% mass. One case, not a target.Mougin 2026B+Will a hard evening session cost me sleep?In 14,689 active adults, a maximal session ending 2 h before bedtime went with sleep 36 min later and 22 min shorter than a light one; easier ones ending ≥4 h before did not. Observational.Leota 2025BDoes leg strength relate to W′?In 11 elite male cyclists, knee-extensor max torque tracked W′ (r = 0.87; our 95% CI 0.57-0.97), thigh volume borderline (r = 0.60, p = 0.05), CP neither. Correlation only: strength-for-W′ is…Kordi 2018C+I stopped for 3 months at 53 — how much did I lose?One trained triathlete lost 7% of VO2max (9% per kg) and 10% of peak power in 12 weeks off, and 12 weeks back (full volume by week 7) restored it. n = 1; one test per point.Zanou 2024BDoes lifelong endurance training keep fast-twitch muscle?In 31 men over 65, lifelong lifters had young-like type II fibres, 1RM and RFD; lifelong runners resembled active peers. Cross-sectional, 8-13 per group: selection not excluded.Tøien 2023C+Can 30 years of endurance training make one identical twin very different?In one pair aged 52, the trained twin had 12.4 ml/kg/min more VO2max and 8.6% lower body-fat % but smaller, weaker muscle. One pair: what is possible, not typical.Bathgate 2018BDoes activity itself make the difference if genes are equal?In 10 identical male twin pairs aged 32-36, the twin more active for 3 years was leaner and more insulin-sensitive. Cross-sectional, abstract only: not proof of cause.Rottensteiner 2015B+Does a poor responder to one kind of training do better on another?34 untrained young twin pairs: strength followed 12 wk of lifting, VO2max 12 wk of endurance; "responder" was any change >0 in one test, so the rescue claim is unproven.Marsh 2020BDoes elite-level running shorten life?Not in the first 200 sub-4 milers: they lived 4.7 years longer than men of their age, era and country. No control for wealth, smoking, health or genes, so "not shorter", not "running added years".Foulkes 2024C+Does lifelong hard training stop VO2max falling?Not for a marathon world-record holder: 68.1 at 49 → 43.6 at 77 (−36%) on 10-15 h/wk; he stayed high by starting high. Enlarged atria, then AF (link unproven). n = 1.Foulkes 2024C+What does a 76-year-old marathon world-record holder look like?VO2max 47.9 (best known for a woman >75), HRmax 180 vs 155 predicted, marathon at 88% of VO2max, ordinary economy; ~90% easy running. n = 1: possible, not typical.Van Hooren 2025C+Can an 80-year-old have a 35-year-old's VO2max?One Norwegian man did: 50 mL/kg/min, ~90 min/wk structured training, ~3 h/day active. Decline from a recalled ~75 at 25 was ordinary; he started high. n = 1: possible, not typical.Karlsen 2015BDo on-bike isometric pushes at crank angles raise sprint power?In 24 elite track sprinters, 6 weeks of 3-s max pushes at 3 angles instead of the heavy lift: W/kg +4.3% vs −0.5%; watts +2.9%, not above controls. Not randomised.Kordi 2020B+Will slow bodyweight strength work make a runner faster?In 34 soldier-runners, 4 wk of 84-s sets (7-s reps) raised knee torque and jump; 3000 m gains (−2.8% vs −0.8% in controls) were not significant. Short, underpowered; no economy data.Martins 2026C+Do slow reps switch on mitochondria?One bout of 30% 1RM at 6 s up/6 s down to failure raised mitochondrial protein synthesis 114% at 0-6 h; fast reps short of failure did not, but both did by 24-30 h. n=8, acute, not mitochondrial…Burd 2012BDoes light lifting to failure add capillaries and mitochondria?In 10 men, 6 wk of 30% 1RM squats to failure raised type I capillary contacts ~18% and respiration ~30%, not mitochondrial proteins. Normal tempo; no non-training control.Pignanelli 2020B+Do light loads to failure build slow fibres and mitochondria?In 21 men, 30% 1RM to failure grew type I fibres like 80% and alone raised mitochondrial dynamics proteins; volume-matched 30% short of failure did not. Tempo unstated; ~7/arm.Lim 2019A-Do slower reps build more muscle?In 14 trials, ~3.5-s reps grew muscle no better than ~1-s reps (difference 0.09 favouring faster, CrI −0.04 to 0.22). Usually one phase was slowed; reps over 4.5 s were not tested.Enes 2025A-Does a slow tempo grow more muscle?A meta-analysis of 8 trials to failure found similar growth for reps of 0.5-8 s; reps over 10 s looked worse (few studies). Muscle size only: no fibre-type, mitochondrial or endurance data.Schoenfeld 2015BDoes slow, no-relaxation squatting make you more powerful?In 16 young men, 8 weeks of 50% 1RM squats at 3 s down / 3 s up grew the quads 6-10% and squat 1RM 10%; jump height and leg power did not change significantly.Usui 2016B+Does slow, no-relaxation lifting at 50% 1RM build muscle after 60?In 35 adults aged 59-76, 12 weeks twice weekly raised thigh muscle thickness and knee strength; normal speed at that load added little size. Abstract only.Watanabe 2013BDoes slow, no-relaxation squatting change how you pedal?In 24 non-cyclists, 13 weeks of LST squats made pedal force and quad EMG more even (variation -18%, -21%); heavy squats did not. Performance effect unknown.Tanimoto 2009B+Does whole-body slow, no-relaxation lifting at ~55-60% 1RM work?In 36 untrained men, 13 weeks twice weekly: muscle thickness +6.8% and 1RM +33% vs +9.1% and +41% with ~80-90% 1RM. About three-quarters of the heavy gains; abstract only.Tanimoto 2008B+Does slow, no-relaxation lifting at ~50% 1RM build muscle?In 24 untrained men, 12 weeks of 3 s up / 3 s down to failure grew the quads like ~80% 1RM (+5.4% vs +4.3%); normal speed at that load did not. Small trial.Tanimoto & Ishii 2006C+Does no-relaxation training at 50% 1RM match heavy lifting?The IBMP lab's summary: it builds strength and size, but less than 80-85% 1RM, with growth shifted to type I fibre area. Abstract only, no numbers.Vinogradova 2013BDoes 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.Popov 2006A-Does training at long muscle lengths grow more muscle?A Bayesian meta-analysis of 12 small trials found only trivial extra regional growth (SMD 0.05-0.09), slightly more distally. Mostly untrained people, modest length contrasts.Varovic 2025