Title

Dehydration and Symptoms of Delayed-Onset Muscle Soreness in Hyperthermic Males

Document Type

Article

Publication Date

2005

Abstract

Context: Exercise in the heat produces cellular conditions that may leave skeletal muscle susceptible to exercise-induced microdamage. Delayed-onset muscle soreness (DOMS) is a clinical model of contraction-induced skeletal muscle injury.

Objective: To determine whether thermoregulation during exercise heat stress adversely affects muscle injury and the accompanying DOMS.

Design: Randomized group test-retest design.

Setting: Laboratory.

Patients or Other Participants: Ten healthy male volunteers were randomly assigned to either the euhydration/hyperthermic or dehydration/hyperthermic group.

Intervention(s): Participants were randomly assigned to treadmill walking in a hot, humid environmental chamber (40°C and 75% relative humidity) with either oral rehydration (euhydration/hyperthermic) or fluid restriction (dehydration/hyperthermic). Immediately after heat exposure and while hyperthermic, participants performed an eccentrically biased downhill run to induce DOMS.

Main Outcome Measure(s): We measured DOMS characteristics pre-exercise and at 0.5, 24, 48, 72, and 96 hours postexercise.

Results: Treadmill exercise and exposure to the hot ambient environment elicited a 0.9% body mass loss for the euhydrated/ hyperthermic (mean rectal temperature after 60 minutes of heat-stress trial = 38.2 ± 0.4°C) and 3.3% body mass loss for the dehydrated/hyperthermic participants (mean rectal temperature after 60 minutes of heat-stress trial = 38.1 ± 0.4°C). Quadriceps perceived pain was significantly higher (F5,40 = 18.717, P ≤ .001) than baseline at 24 and 48 hours postexercise, following the classic pattern of DOMS. Overall lower extremity perceived pain was significantly higher for the dehydration/hyperthermia group than the euhydration/hyperthermia group (F1,8 = 6.713, P = .032). Punctate tenderness of the vastus lateralis for the dehydration/hyperthermic group was 6.9% higher (F5,40 = 4.462, P = .003) than for the euhydration/ hyperthermic group. No clinically important findings were revealed for passive range of motion for knee flexion. For both groups, quadriceps isometric strength (F5,40 = 12.924, P ≤ .001) was 17.5% and 20.0% lower at 0.5 hours postexercise than at 72 and 96 hours postexercise, respectively. Further, quadriceps isometric strength remained 10.5% reduced at 24 hours postexercise compared with 96 hours postexercise.

Conclusions: Skeletal muscle microdamage, indirectly evidenced by DOMS, was exacerbated in hyperthermic participants dehydrated by exercise in a hot ambient environment. Individuals performing novel exercise, particularly with a significant eccentric component, should use caution when training in a hot, humid environment and implement frequent rest and rehydration breaks.

Comments

This article was originally published in Journal of Athletic Training, volume 40, issue 4, in 2005.

Peer Reviewed

1

Copyright

National Athletic Trainers' Association, Inc.