Metabolic and muscular responses during and after a 100 km hill walk

Aim: Aim of the study was to assess different metabolic and muscular responses of recreational hikers during and after a hill walk of 100 km duration.

Methods: Nine subjects (6 males and 3 females) completed the 100 km hill walk within 40 hrs. Physiological and muscular responses, and biomarkers were measured during- and 18 hrs after the exercise.

Results: On average, exercise intensity was moderate with reference to %HRmax (64±7.1), with a declining trend. Energy expenditure ranged from 102.5 kcal/km to 186.2 kcal/km in different sections. Using a visual analog scale, left and right quadriceps, and left and right calf muscles had elevated values of perceived muscular soreness (5±2.4, 5±2.4, 4.6±2.7 and 4.6±2.7, respectively). Ranges of motion at hip and knee joints decreased at 47.4 km (P<0.05). Creatine kinase for male subjects increased 16-fold (from 106.8±95 U/L to 1747.6±1834.2 U/L) at 79.6 km. Creatine kinase-MB and lactate dehydrogenase for males were also elevated at 79.6 km and peaked at 100 km. Following recovery, creatine kinase for male subjects was still slightly higher than resting level (321.1±283.6 U/L vs. 106.8±95 U/L). Ranges of motion at hip and knee joints were higher than pre-walk level (P<0.05).

Conclusion: The data suggest that healthy recreational hikers with average physical fitness can complete a 100 km hill walk within 40 hours without showing excessively stressful physiological responses. However, complete recovery would probably require more than 18 hours.