Effect of hydration on delayed muscle soreness in males dehydrated in a hot ambient environment

The purpose of this study was to determine the effects of hydration on delayed onset of muscle soreness (DOMS) of the lower extremity induced by eccentric activity in participants dehydrated by fluid deprivation and exposure to a hot ambient environment. Participants were randomly assigned to either an euhydrated or a dehydrated condition, exercised by walking for 5 min at 2.5 mph and 55 min at 3 mph in a hot ambient environment of 40°C and 75% relative humidity, and performed a 45-min downhill run (-12% grade from the horizontal plane). Euhydrated participants consumed water ad libitum.;Body mass decreased by 3.3 and .9% during the exposure to the hot ambient environment for the dehydrated and euhydrated participants, respectively. Rectal and mean body temperatures increased in both conditions. Heart rate was greater in both conditions and higher in the dehydration condition.;Isometric peak torque was lower at 30 min following downhill running and higher at 96 hr for both conditions. No differences were observed at 24, 48, and 72 hr.;Passive range of motion for knee flexion, subjective perception of muscle pain and soreness of the quadriceps muscle group and the lower extremity using a visual analog pain scale (VAPS), and punctate muscle tenderness were the criteria of DOMS. Downhill running did not influence passive range of motion of knee flexion in either condition. VAPS scores were greater for both conditions from pre-test scores and between conditions at 24 and 48 hr following downhill running. More lower extremity soreness was reported at 30 min and 72 hr in the dehydration condition and was also greater at 24 and 48 hr following downhill running than in the euhydrated condition. Dehydration resulted in greater punctate muscle tenderness of the rectus femoris, vastus medialis, and vastus lateralis at 48 hr post-downhill running and also at 72 hr in the vasti muscles.;It was concluded that downhill running induces DOMS in participants exposed to a hot ambient environment. Participants who were also dehydrated had greater subjective perceptions of muscle soreness and punctate muscle tenderness than euhydrated participants.