Endogenous Opioid Peptides After Floatation Therapy in Resistance-Trained Men

Kraemer, WJ, Caldwell, LK, Post, EM, Volek, JS, Hagen, JM, Newton, RU, Häkkinen, K, Omonije, O, and Maresh, CM. Endogenous opioid peptides after floatation therapy in resistance trained men. J Strength Cond Res38(10): 1808–1812, 2024—Floatation-restricted environmental stimulation therapy (Float-REST) has shown improvements in muscle soreness and fatigue. To determine whether float influences the release of beta-endorphin (β-End) and proenkephalin (ProEnk) after acute heavy resistance exercise, 11 healthy resistance-trained men (age: 22.5 ± 2.3 years; height: 176.4 ± 6.0 cm; body mass: 85.7 ± 6.2 kg, back squat one-repetition maximum: 153.1 ± 20.1 kg; strength-to-mass ratio: 1.8 ± 0.2) completed a within-subject, cross-over controlled study design. Subjects completed 2 exercise testing blocks separated by a 2-week washout. In one block, a 1-hour float session followed the high-intensity resistance exercise protocol (6 × 10 back squats at 80% 1RM, 2 minutes rest). By contrast, recovery in the alternate block consisted of a passive sensory-stimulating control. Blood samples were collected at 5 time points—before exercise, immediately after exercise, after1-hour recovery treatment, 24 hours after exercise, and 48 hours after exercise. Samples were analyzed in duplicate for β-End and ProEnk using ELISA immunoassays. Mean differences were assessed using repeated-measures ANOVA. Plasma β-End demonstrated the expected significant (p≤ 0.05) increase following resistance exercise in both treatment conditions. There were no significant changes with exercise stress for ProEnk precursor peptide. The absence of significant differential changes following Float-REST suggests that these opioid peptides may not underlie the deep relaxation experiences commonly reported with this intervention in trained men. However, practically, it shows that β-End remains consistently similarly increased to high-intensity exercise stress. However, the ProEnk concentrations are detectable and stable but do not respond to the workout protocol, which, as a primary opioid peptide precursor, suggests paracrine cybernetics in the circulation may exist.