Low-Volume Sprint Interval Swimming Is Sufficient to Increase Blood Metabolic Biomarkers in Master Swimmers

ABSTRACT

Purpose: Sprint interval exercise is a time-efficient way of inducing beneficial adaptations. However, little is known about its minimal effective volume, especially in swimming. The aim of the present study was to evaluate and compare the effects of two sprint interval swimming sets of different low volumes on blood biomarkers. Method: Twenty-one master swimmers [11 females aged 38.5 (8.5) years, 10 males aged 42.7 (5.7) years] completed two freestyle swimming sets of 4 × 50 m and 4 × 25 m at maximal intensity and a work-to-rest ratio of 1:1, on different days, in random and counterbalanced order. Blood samples were taken before, immediately after and one hour after exercise for determination of a number of biochemical parameters. Results: Swimming speed was higher in the 4 × 25-m set. Lactate, glucose, insulin, glucagon, cortisol, and reduced glutathione increased immediately post-exercise, while uric acid increased 1 h post-exercise (p < .05). All aforementioned biomarkers, excluding glucagon, increased more with the 4 × 50-m set, compared to the 4 × 25-m set (p < .05). Session rating of perceived exertion was higher after the 4 × 50-m set (p = .011). Conclusion: Both sprint interval swimming sets elicited increases in blood biomarkers in master swimmers. The set of higher volume elicited greater increases in most of the biochemical markers studied but also in subjective load. Thus, although the set of higher volume was more efficient in perturbing blood biomarkers, even the very low-volume set induced metabolic stress that may trigger adaptive mechanisms.

KEYWORDS:

• Exercise-induced stress
• glucose
• lactate
• session rating of perceived exertion

Additional information

Funding

This research was co-financed by Greece and the European Union (European Social Fund, ESF) through the Operational Program “Human Resources Development, Education and Lifelong Learning” in the context of the project “Reinforcement of Postdoctoral Researchers” [MIS-5001552], implemented by the State Scholarships Foundation (ΙΚΥ).