Why we train the way we do.

A review of 11 studies found you gain the most strength in whatever you lift first in a session, while you are fresh. Muscle growth came out the same whatever the order.

What we do with it. Your main lift (we call it the KPI) sits at the top of the session. Everything after it is ordered for time and flow.

Source: Nunes et al. 2021

Holding a stretch for 60 seconds or more just before training cut performance by about 4.6% on average. Holds under 60 seconds cost about 1%, and moving stretches gave a small lift of about 1.3%. A newer review of 83 studies agrees on long holds and maximum strength, and found no harm to jumping or sprinting.

What we do with it. Pre-work uses moving stretches and short holds. Long holds are saved for the recovery block at the end.

Source: Behm et al. 2016, Warneke & Lohmann 2024

Foam rolling before training improved flexibility by about 4% and sprint performance by under 1%. Those are real effects, and they are small.

What we do with it. A short roll in pre-work if it helps you feel ready to move. We do not sell it as a fix for anything.

Source: Wiewelhove et al. 2019

Across six trials and 6,574 footballers, a structured warm-up program of running, strength, balance and jumping drills cut injuries overall by 39%. A 2025 review of three trials (3,833 players) found about a third fewer ankle injuries with the same program.

What we do with it. Our pre-work borrows those ingredients, including feet and ankle work on many lower body days. Nobody has tested our version in a gym, so we do not claim those numbers for it.

Source: Thorborg et al. 2017, Eser et al. 2025

An analysis of 67 studies and 2,058 people found that both strength and muscle growth rise with the number of hard sets you do each week. The returns shrink as you add more, and strength levels off sooner than size.

What we do with it. Programs are built on a moderate number of hard sets per lift, and sets get added slowly and on purpose.

Source: Pelland et al. 2026

Across 67 studies, how often a muscle was trained made next to no difference to growth once the total weekly work was counted. Training a lift more often did help strength a little, with shrinking returns. Newer work from the same researchers, not yet peer reviewed, suggests a ceiling on what one session can do: beyond about 11 sets for a muscle, or about two heavy sets of a lift for strength, extra sets in the same session stop adding much.

What we do with it. So frequency still matters, for a different reason. Once you need more work than one good session can hold, a second session is how you get it, and lifts improve with practice. Our four-day split hits the main movement patterns about twice a week for exactly that. If you can only make two or three sessions, we keep the total work and spread it differently.

Source: Pelland et al. 2026, Remmert et al. 2025, Schoenfeld, Ogborn & Krieger 2016, Schoenfeld, Grgic & Krieger 2019

For strength, experienced lifters gained more resting over two minutes between sets, and newer lifters did well on 60 to 120 seconds. For muscle growth, a 2024 analysis of nine studies found a small benefit to resting longer than a minute and nothing extra beyond about 90 seconds.

What we do with it. The app runs a rest timer that your coach sets. If you switch it off, it shows you this research first. Our default rest times are a house rule, so if you are experienced and the set is heavy, take longer.

Source: Grgic et al. 2018, Singer et al. 2024

A 2025 meta-analysis of 19 studies found supersets cut session time by about 37%, with strength and muscle gains similar to normal sets. They do feel harder.

What we do with it. Supersets live in the secondary and accessory blocks. Your main lift stays on its own with full rest.

Source: Zhang et al. 2025, Iversen et al. 2021

Pooled long-term studies link muscle-strengthening exercise with roughly 15% lower risk of dying over the follow-up period, with most of the benefit at 30 to 60 minutes a week. People who did both strength and aerobic exercise had about 40% lower risk. These studies show a link, they cannot prove cause.

What we do with it. Two strength sessions a week is the floor we recommend for every member, whatever else you do.

Source: Momma et al. 2022

Strength can be held for months on as little as one session a week, provided the weight stays heavy. Volume and frequency can drop a long way before you lose much.

What we do with it. For holidays and busy seasons we shorten sessions and keep the load on the bar.

Source: Spiering et al. 2021

A meta-analysis found steady endurance training raised aerobic fitness by about 4.9 units (mL/kg/min) and high-intensity intervals by about 5.5. Intervals had a small edge, and both worked.

What we do with it. ESD sessions mix interval formats with longer continuous efforts across the month.

Source: Milanović et al. 2015

Circuit-style strength training improved both aerobic fitness and upper body strength.

What we do with it. Stations, chippers and EMOM formats use loaded movements, so a conditioning class still counts towards getting stronger.

Source: Muñoz-Martínez et al. 2017

Across 43 studies, doing strength and aerobic training in the same program did not reduce maximum strength or muscle growth. Explosive power took a small hit when both were done in the same session.

What we do with it. Strength days and ESD days sit apart where we can, and any power work is done fresh at the start.

Source: Schumann et al. 2022

A 2024 meta-analysis of 31 studies and 652 runners found heavy lifting gave a small improvement in running economy, and heavy lifting combined with jump training a moderate one. An earlier review of two to three sessions a week put the gain at 2 to 8%.

What we do with it. Event programs keep strength work in all the way through.

Source: Llanos-Lagos et al. 2024, Blagrove et al. 2018

The best results came from about a two-week taper that cut training volume by 41 to 60% while keeping the intensity and the number of sessions the same. A 2023 analysis of 14 studies in endurance athletes agreed: up to three weeks, volume brought down gradually by 41 to 60%, intensity and frequency unchanged.

What we do with it. Event plans in the coach app work back from your date and finish with a taper.

Source: Bosquet et al. 2007, Wang et al. 2023

A 2024 meta-analysis of 17 studies found this "polarised" mix gave a small extra lift in aerobic fitness compared with other mixes, and only in highly trained athletes on shorter programs. It made no difference to time trial performance.

What we do with it. We use this shape for some members training for endurance events because it is simple to follow. We do not claim it beats other sensible plans.

Source: Silva Oliveira et al. 2024, Stöggl & Sperlich 2014

A review found that rating how hard a session felt, multiplied by how long it ran, is a valid and reliable way to track training load across many sports.

What we do with it. Coaches set effort targets on your sets as RPE or reps in reserve. A whole-session rating is on our list to add.

Source: Haddad et al. 2017

Sauna use is safe for most healthy people. The clear cautions are alcohol, unstable chest pain, a recent heart attack and severe narrowing of the aortic valve.

What we do with it. Never sauna after drinking. If you have a heart condition, are pregnant or are unsure, check with your GP first. Drink water before and after.

Source: Hannuksela & Ellahham 2001

For muscle soreness after hard exercise, the best results came from water at 11 to 15 degrees for 11 to 15 minutes. A 2025 analysis of 55 trials agreed, ranking 10 to 15 minutes at 11 to 15 degrees best for soreness. Colder water, 5 to 10 degrees for the same time, ranked best for getting jump performance back.

What we do with it. If you are using cold water for soreness, that is the dose with the evidence behind it. A short, very cold dip is a different experience and has not been tested as well.

Source: Machado et al. 2016, Wang, Wang & Pan 2025

In a meta-analysis comparing recovery methods, massage came out on top for reducing soreness and the feeling of fatigue. A 2020 review of 29 studies found soreness about 13% better after massage and no direct benefit to strength, sprint, jump or endurance performance.

What we do with it. If soreness is the problem, massage is the first thing we would point you to. We do not sell it as a way to perform better.

Source: Dupuy et al. 2018, Davis, Alabed & Chico 2020, Poppendieck et al. 2016, Crane et al. 2012

Training dehydrated cut strength by about 5.5% and muscle endurance by about 8.3%. Extra protein adds to the gains from lifting up to about 1.6 grams per kilo of bodyweight a day, with no further benefit above that. Creatine is the most studied supplement in sport, effective at 3 to 5 grams a day and safe in healthy people.

What we do with it. These are general numbers and not personal advice. Talk to a dietitian or your GP about what suits you.

Source: Savoie et al. 2015, Morton et al. 2018, Kreider et al. 2017

Two sleep medicine societies reviewed the evidence and agreed that adults should sleep seven or more hours a night on a regular basis.

What we do with it. Snuuzie plans your lights-out time around your sleep goal and tomorrow's first commitment.

Source: Watson et al. 2015

In a study of about 61,000 adults wearing trackers, people with more regular sleep and wake times had 20 to 48% lower risk of dying during the study than the least regular fifth. Regularity predicted this better than how long people slept, and length still mattered. A National Sleep Foundation expert panel reached the same view: consistent bed and wake times matter for health, safety and performance.

What we do with it. Snuuzie plans around your real calendar, so your times can shift a little from day to day, and that is fine. The big swings are what count. Helping you keep free-day wake-ups closer to your normal one is the next thing we are building.

Source: Windred et al. 2024, Sletten et al. 2023

A review of 24 studies found caffeine took about 45 minutes off the night and cut into deep sleep. It worked out that a coffee (about 107mg) wants to be at least 8.8 hours before bed, and a pre-workout (about 217mg) at least 13.2 hours. In a separate trial, 400mg taken six hours before bed cost more than an hour of sleep, and the people taking it did not notice.

What we do with it. Switch on the Caffeine curfew and Snuuzie puts a "last one by" time on your day, 9 hours before lights out by default. It moves when your bedtime moves, and you can set it anywhere from 6 to 13 hours.

Source: Gardiner et al. 2023, Drake et al. 2013

A meta-analysis found alcohol reduces REM sleep from about two standard drinks, and the more you drink the bigger the effect.

What we do with it. Snuuzie does not track drinks. It is worth knowing on the nights that count.

Source: Gardiner et al. 2025

Sleep is best in a room around 19 to 21 degrees. A warm shower or bath one to two hours before bed helps people fall asleep faster.

What we do with it. Snuuzie does not coach these yet. Both are free and worth trying.

Source: Harding et al. 2019, Haghayegh et al. 2019

Across the research, a short night of sleep reduced next-day physical performance by about 7.5% on average. Several short nights in a row reduce the force you can produce on big compound lifts.

What we do with it. If you have slept badly, tell your coach. Dropping a set today is a smart call.

Source: Craven et al. 2022, Knowles et al. 2018

A systematic review found health habits take a median of about two months to form, with a range from 4 days to 335. In the best-known study, 96 people averaged 66 days, and missing a single day did not derail them.

What we do with it. We describe one climb as the start of a habit. Most people need more than one.

Source: Singh et al. 2024, Lally et al. 2010

A meta-analysis of 138 studies found that monitoring your progress makes you more likely to reach a goal. The effect was bigger when progress was written down and when other people could see it.

What we do with it. Daily ticks and a team board are the centre of every climb. The board is there so people can cheer each other on.

Source: Harkin et al. 2016

Game features such as points and streaks gave a small to moderate lift in physical activity. Most of that lift was gone once the game stopped.

What we do with it. Streaks, wins and the gym TV are there to get you started and keep it fun. What keeps people training long term is their coach and the people they train with.

Source: Mazeas et al. 2022

People who enjoy exercise while they are doing it are more likely to keep going. Feeling good afterwards did not predict it.

What we do with it. Every exercise can be made easier or harder with a swipe, and you can choose fewer sets on a rough day. A session you can finish beats one you dread.

Source: Rhodes & Kates 2015

Across 33 trials and 1,877 people, strength training reduced depressive symptoms by a moderate amount. A 2024 analysis of 218 trials found strength training, walking or jogging and yoga were all effective, and that harder exercise helped more. The better-run trials showed smaller effects, so the true size is probably more modest.

What we do with it. This is a reason to train. It is not a treatment plan. If you are struggling, talk to your GP, and let your coach know so we can train around how you are feeling.

Source: Gordon et al. 2018, Noetel et al. 2024

In those 33 trials, the lift in mood did not depend on how many days a week people trained, how hard they went, how much work they did or whether they got stronger. Coached programs did far better than partly coached ones.

What we do with it. A short session still counts, and so does an easy one. It is also why coaching sits at the centre of what we do.

Source: Gordon et al. 2018

Across 16 studies and 922 people, strength training gave a small reduction in anxiety symptoms, larger in healthy adults. How often, how hard and how long people trained made no difference.

What we do with it. Another reason the minimum is worth doing.

Source: Gordon et al. 2017

Across 16 trials and 1,871 adults, exercise programs improved self-efficacy, which is your belief that you can do what you set out to do. In 10 to 16 year olds, strength training improved confidence in the gym, how strong they felt and how they rated themselves overall. The clearest gains are in confidence about training itself. How far that carries into the rest of life is less certain, and nobody has tested whether training more often builds it faster.

What we do with it. We set targets you can hit, then move them. Personal bests, step-ups and ticking off a hard session are the proof you did it.

Source: Ghayour Baghbani et al. 2023, Collins et al. 2019

A meta-analysis found that planning training around daily heart rate variability gave no clear advantage over a normal plan. A popular workload ratio used to flag "too much, too soon" has also been heavily criticised by the researchers who tested it.

What we do with it. We use wearable data to start a conversation with your coach. It does not decide your session, and one good morning reading cannot tell you today is the day for a personal best.

Source: Manresa-Rocamora et al. 2021, Impellizzeri et al. 2020