How Often Should You Work Out? (EXPERIMENT)
In a Nutshell
A 10-week experiment with 200 lifters found that training three days per week produced nearly identical muscle growth (0.75 inches) as training six days per week (0.83 inches), despite doing half the sets. The six-day group struggled with accumulating fatigue and unconsciously held back effort, while the three-day group trained harder knowing they had fewer sessions. Higher training frequency with full-body workouts (packing all volume into three sessions) slightly outperformed both, suggesting quality and recovery matter more than total volume once reaching 15-20 sets per muscle per week.
These notes were generated by AI and may contain inaccuracies.
What if half the time and effort you're spending in the gym isn't actually doing anything? Research was conducted on over 200 people and findings went against conventional training knowledge.
Since getting into lifting, training typically involved six hard workouts a week. According to latest research, more sets should equal faster growth. However, most studies only tested high volumes on one or two muscles at a time, not entire body.
Drew was one of 200 lifters recruited for a 10-week experiment. Each lifter was randomly assigned into one of two groups.
Group 1: Six-Day Training
- Training six days per week using push-pull-leg split
- Around 20 sets per muscle per week
- Same routine followed for years
Group 2: Three-Day Training
- Also doing push-pull-leg split
- Only three workouts per week
- Same muscles worked, but half the workouts and half the sets
Matt predicted the group training twice as much should build the most muscle. He was worried about building any muscle at all with the three-day plan, stating: "I don't know. I hope I don't get fat."
To control nutrition, every subject followed a small calorie surplus with minimum daily protein target, tracked in Built with Science app. Anyone not consistent was kicked out. Both groups were balanced for gender and had equal numbers of beginners and intermediates.
Participants submitted weekly circumference measurements of flexed and unflexed muscles. This approach was chosen to expand sample size rather than using high-tech body composition measurements on smaller groups.
Dr. Eric Trexler, a statistician and muscle growth researcher, helped design the experiment and independently analyzed the data.
After just 3 weeks, the 6-day group struggled to keep up. One participant missed morning workouts and had to do them at night, stating they started to dislike the 6-day split.
Subjects rated program difficulty at the end of each week:
- Three-day group rated workouts as feeling easier over time
- Six-day group ranked workouts as much harder and never got easier
One three-day participant stated: "Going into the gym only 3 days a week, I am giving 110% rather than cutting corners here and there."
Both groups were confident their plans were working, but the 6-day group repeatedly believed their program was doing more to maximize growth. One participant experienced nausea and vomiting after leg exercises.
Some three-day group members weren't sure if they were seeing results, with one stating their belly was growing while the rest stayed the same, and another reporting no increased strength or fitness.
In the last weeks, the three-day group reported feeling stronger and lifting heavier. One participant stated: "I feel way stronger than I did last week. I'm starting to feel like I'm in my 30s again."
Three-day participants pushed harder because they had fewer days: "I think maybe I did push myself harder because I only had 3 days. I'm like, we got to make these count."
Six-day group members talked about training as if trying to survive, with one stating: "Am I enjoying the program so far? No, I'm not." Another said they wouldn't recommend this program to others.
Dr. Eric Trexler analyzed the data and confirmed high-quality, realistic data collection. All groups achieved statistically significant growth.
- Six-day program: 0.83 inches combined growth on average
- Three-day push-pull-legs: 0.75 inches combined growth
- Difference was not statistically significant
Despite three-day group doing half the training, they grew statistically the same as the six-day group.
Research suggests going from 10 sets per muscle per week to double should yield about 60% more gains. This calculation predicted six-day group should have seen 1.2 inches combined growth instead of 0.83 inches.
Dr. Eric Helms explained muscles don't care about sets written in workout plans - they respond to actual muscle building stimulus. Some people grow better dropping from 20+ sets to teens because actual dose was higher when volume decreased.
A 2014 study had participants do 12 sets of maximal isometric bicep contractions. Half were told they'd do 12 sets, half were told they'd do 6 sets. The group knowing they had 12 sets produced less power than those who thought they only had 6 sets.
Six-day participants reported needing to pace themselves more due to volume accumulation. Despite app prompts to push close to failure, knowing they had twice as much training could cause subconscious holding back or form breakdown.
Research studies supervise training to ensure participants push hard and maintain form. A new study published 3 days before this video showed supervised groups grew more than unsupervised groups doing identical plans, with fat-free mass gains favoring supervised group by more than a pound.
Test 1: Rep Speed
Last few reps should move much slower than first few reps. If not, likely stopping too soon.
Test 2: Rep Drop Off
With same weight across three sets, reps should decrease (e.g., 12, 11, 9-10). Flat or increasing reps indicate insufficient effort in earlier sets.
Test 3: Progressive Overload
Check if consistently adding reps or weight on main lifts over 2-3 months. No progress despite 5-6 day training suggests cutting back volume.
Try cutting volume for a training block or two while pushing intensity. Reduce from three or four sets to two hard, high-quality sets per exercise.
For those who train hard with dialed form regardless of set count, a follow-up study compared 36 weekly sets against 9 sets for arms and thighs in trained lifters under supervision.
Data slightly favored higher volumes but differences were non-meaningful. Marginal returns diminish significantly once reaching teens and 20s of sets.
For someone like Eric aiming to become top five natural bodybuilder, the extra time investment (10-11 hours weekly) versus potential gains creates difficult trade-offs.
A third group packed all six-day volume into three full-body workouts with supersets. This group got the best results: 0.87 inches average growth, slightly greater than six-day push-pull-legs.
The advantage wasn't volume (matched with six-day program) but frequency. Three-day full body training hit each muscle group more frequently, avoiding performance decline from consecutive sets.
Eric Helms does six workouts weekly split into two daily sessions (morning and evening) to maximize volume while maintaining workout quality.
- For maximum growth with proper effort maintenance: higher volume options with specific set recommendations and workout splits
- For solid gains with less gym time or current high-volume non-responders: reduced frequency approaches
Personal approach involves training hard four to five times weekly, achieving 60-70% of maximum potential growth.
Any plan produces results with consistency and good nutrition support. Built with Science Plus app provides personalized workout and nutrition plans adjusting weekly based on body response.
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