Forskning

April 28, 2013

Caffeine increases performance in cross-country bouble-poling time trial exercise

H K Stadheim et al, 2013, Caffeine increases performance in cross-country bouble-poling time trial exercise, Medicine & Science in Sports & Exercise, Accepted Manuscript.

ABSTRACT
Purpose: Caffeine (CAF) improves performance of both short and long duration in running and cycling where performance relies on power output, and endurance capacity of leg muscles. No studies have so far tested effects of CAF while using the double poling (DP) technique in cross country skiing (XCS). When DP arm muscles provide the speed generating force, and therefore play an important role to performance outcome. The metabolism of arm muscles differs from that of leg muscles. Thus, results from studies on leg muscles and CAF may not be directly applicable to exercises while DP in XCS. The purpose of our study was therefore to investigate effects of CAF on exercise performance in DP. Method: Ten highly trained male cross-country skiers (VO2max running, 69.3±1.0 ml・kg-1・min-1) performed a placebo (PLA) and CAF trial using a randomized, double-blinded, cross-over design. Performance was assessed by time to complete an 8 km cross country DP performance test (C-PT). CAF (6 mg・kg-1) or PLA was ingested 75 min before the C-PT. Results: CAF ingestion reduced times to complete the 8 km C-PT from 34:26±1:25 to 33:01±1:24 min (p<0.05). The subjects maintained higher speed and heart rate throughout the C-PT, and lactate was higher immediately after the C-PT with CAF exposure compared to PLA. Subjects reported lower rating of perceived exertion at submaximal intensities during CAF compared to PLA, although heart rate was similar. Conclusion: CAF intake enhances endurance performance in an 8 km C-PT where arm muscles limit performance. CAF ingestion allowed the participants to exercise with a higher heart rate, and work intensity, possibly by reducing perception of effort or facilitating motor unit recruitment.