Endogenous Opioid Peptides After Floatation Therapy in Resistance-Trained Men

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Abstract 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 Res 38(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.