Do Float Tanks Boost Your Endorphins After a Workout? A Study Says No

Within-subject crossover controlled design. 11 resistance-trained men completed two exercise blocks separated by a 2-week washout. Each block involved the same high-intensity protocol (6 sets of 10 back squats at 80% of their one-rep max with 2-minute rest). After one session, they did a 1-hour float (Float-REST); after the other, a passive sensory-stimulating control. Blood was drawn at 5 timepoints: before exercise, immediately after, after recovery, 24 hours later, and 48 hours later. Beta-endorphin and proenkephalin were measured using ELISA immunoassays. Differences were assessed using repeated-measures ANOVA.

Float tanks have become popular in athletic recovery, with many users reporting profound relaxation and reduced soreness. This study tested whether that relaxation is mediated by opioid peptides — the body's natural painkillers. The finding that it isn't means the subjective benefits of floatation likely come from other mechanisms (sensory deprivation, muscle relaxation, reduced cortisol) rather than an extra endorphin boost. This helps separate the science from the marketing around float therapy.

This study contributes to a growing body of research trying to understand why certain recovery modalities 'feel' effective. The finding that float tank relaxation isn't opioid-mediated shifts attention to other mechanisms — sensory deprivation effects on the nervous system, muscle unloading in salt water, or psychological components. It also adds to our understanding of how opioid peptides respond to exercise, confirming that beta-endorphin is reliably elevated by high-intensity resistance training.

Very small sample (n=11) of young, trained men limits generalizability. Only two opioid peptides were measured — other endogenous opioids (dynorphins, endomorphins) weren't assessed. The 1-hour float session is a specific protocol and different durations may have different effects. Subjective relaxation data wasn't correlated with peptide levels, so we can't directly test whether relaxation and peptide changes are dissociated. The study can't rule out localized opioid peptide changes in the brain that wouldn't appear in blood samples.