Coping with heat stress during match-play tennis: Does an individualised hydration regimen enhance performance and recovery?

Objectives To determine whether an individualised hydration regimen reduces thermal, physiological and perceptual strain during match-play tennis in the heat, and minimises alterations in neuromuscular function and physical performance postmatch and into recovery. Methods 10 men undertook two matches for an effective playing time (ball in play) of 20 min (similar to 113 min) in similar to 37 degrees C and similar to 33% RH conditions. Participants consumed fluids ad libitum during the first match (HOT) and followed a hydration regimen (HYD) in the second match based on undertaking play euhydrated, standardising sodium intake and minimising body mass losses. Results HYD improved prematch urine specific gravity (1.013 +/- 0.006 vs 1.021 +/- 0.009 g/mL; p<0.05). Body mass losses (similar to 0.3%), fluid intake (similar to 2 L/h) and sweat rates (similar to 1.6 L/h) were similar between conditions. Core temperature was higher during the first 10 min of effective play in HOT (p<0.05), but increased similarly (similar to 39.3 degrees C) on match completion. Heart rate was higher (similar to 11 bpm) throughout HOT (p<0.001). Thermal sensation was higher during the first 7.5 min of effective play in HOT (p<0.05). Postmatch knee extensor and plantar flexor strength losses, along with reductions in 15 m sprint time and repeated-sprint ability (p<0.05), were similar in both conditions, and were restored within 24 h. Conclusions Both the hydration regimen and ad libitum fluid consumption allowed for minimal body mass losses (<1%). However, undertaking match-play in a euhydrated state attenuated thermal, physiological and perceptual strain. Maximal voluntary strength in the lower limbs and repeated-sprint ability deteriorated similarly in both conditions, but were restored within 24 h.