Evidence library
The science, with the papers attached
Sexual fitness gets talked about in folklore and sold in supplements. It is, in fact, a measured area of exercise physiology. Here is what the literature actually says, and where we got each number.
Energy cost
Sex sits on the vigorous line. It is not 300 calories.
Frappier and colleagues put accelerometers on 21 young couples and measured actual energy expenditure during sexual activity in their own homes.[2] Men averaged 6.0 METs, exactly the CDC threshold for vigorous activity; women averaged 5.6. The untrained baseline straddles the line. Which side a session lands on is trainable.
Light
<3.0
Moderate
3.0–5.9
Vigorous
≥6.0
Untrained mean · women
5.6
Vigorous line · men
6.0
Trained target
7.5+
Untrained sexual activity sits on the threshold. The training target is to move above it and sustain genuinely vigorous work. [1] [2]
| Activity | METs | kcal | Note |
|---|---|---|---|
| Sexual activity — men | 6.0 | 101 | mean session 24.7 min |
| Sexual activity — women | 5.6 | 69 | mean session 24.7 min |
| Treadmill run — 30 min | 8.5 | 276 | moderate-vigorous pace |
71%
of the intensity of a 30-minute treadmill run
38%
of the calories of that same run
The widely repeated claim that sex burns around 300 calories is false. Nothing in the measured literature supports it. We publish the real number — 101 kcal for men and 69 kcal for women over a mean 24.7-minute session — and we log your sessions against it. Sex earns its place in your training week on the strength of its intensity, not on an inflated calorie figure.
The CDC bands are light <3.0, moderate 3.0–5.9 and vigorous ≥6.0 METs.[1] In the iSexercise ledger, a minute averaging at least 6.0 METs earns the standard 2× vigorous credit. Apple Health receives true elapsed time, never an inflated duration.
Endurance
Aerobic training improves erectile function on its own
+2.8
IIEF-EF points · pooled effect
Pooled across randomised controlled trials, supervised aerobic exercise produced a mean improvement of 2.8 points on the IIEF-EF domain — with no drug, no device and no procedure involved.[4] The effect scales with baseline impairment: the further from aerobic fitness a participant started, the more they gained.
This is the mechanistic core of the endurance pillar. Erectile tissue is vascular tissue. Endothelial function responds to aerobic load the same way it does anywhere else in the body, which is why our Deep Base block is built around accumulated zone-2 minutes rather than novelty.
Control
Pelvic floor training is a first-line physical intervention
Myers and Smith's systematic review found pelvic floor muscle training produced significant improvements in both erectile function and ejaculatory latency across the included trials, with effects comparable to first-line conservative care.[3] Crucially, the effective protocols were progressive — graded hold duration, rapid-contraction work, and explicit relaxation training — not undifferentiated repetitions.
That is exactly how The Control Block is periodised, and why the PQ Control subscore measures three distinct qualities: maximal hold, contraction speed, and release. Most people who train the pelvic floor casually train only the first, and release is frequently the limiter.
Prevalence
Common, under-discussed, and mostly unaddressed
24.2%
of US men meet criteria for erectile difficulty[5]
7.7%
have ever received a formal diagnosis[5]
47.8%
pooled global prevalence of female sexual difficulty[6]
The gap between the first two figures is the whole reason this product exists. Most people affected never enter a clinical pathway at all. A training pathway asks nothing of them except that they train.
Bibliography
Everything cited on this site
- [1]Centers for Disease Control and Prevention. Measuring Physical Activity Intensity: light <3.0 METs, moderate 3.0–5.9 METs, vigorous ≥6.0 METs.
- [2]Frappier J, et al. Energy expenditure during sexual activity in young healthy couples. PLoS ONE. 2013;8(10):e79342. (n=21 couples; mean session 24.7 min)
- [3]Myers C, Smith M. Pelvic floor muscle training improves erectile dysfunction and premature ejaculation: a systematic review. Physiotherapy. 2019;105(2):235–243.
- [4]Aerobic exercise and erectile function: meta-analysis of randomised controlled trials. J Sex Med. 2023;20(12):1369–1379.
- [5]Prevalence of erectile difficulty and diagnosis in US men. J Sex Med. 2024;21(4):296–303.
- [6]Pooled global prevalence of female sexual dysfunction: systematic review and meta-analysis. BMC Women's Health. 2025.