D-22 Free Communication/Poster - Clinical Exercise Physiology 1 (Clinical Exercise Physiology Association): JUNE 2, 2011 1:00 PM - 6:00 PM: ROOM: Hall B
PURPOSE: The purpose of this study was to observe the test-retest reliability of a new handgrip protocol, which could be used as a screening tool for patients with mitochondrial myopathy.
METHODS: 21 physical education (PE) students performed a handgrip exercise protocol at two moments. The retest took place within a week and at the same moment of the day. The all out exercise protocol consists of 2 minutes cyclic handgrip contraction at 20% maximal voluntary contraction (MVC) followed by 1 minute of rest and 2 minutes at 30% MVC. This pattern is continued until exhaustion. Near Infrared spectroscopy (NIRS) was used to measure the deoxygenation in the forearm muscles(m. Palmaris longis, m. flexor carpi ulnaris and m. flexor carpiradialis). Deoxy [Hb+Mb] is often considered as the most important output since it is an equivalent of microvascular oxygen extraction at a certain moment. Prior to the exercise protocol an arterial occlusion of the forearm took place until deoxy[Hb+Mb] did no longer increase (i.e. maximal deoxygenation). The occlusion amplitude is the result of the difference between 30 seconds mean values of the occlusion maximal deoxy [Hb+Mb] and the 30 seconds mean values of the first baseline. The increase in deoxy[Hb+Mb] during each exercise bout was expressed relative to the maximal response during the arterial occlusion. Single measure intraclass correlation coefficients (ICCs) and the kappa test for agreement were used to examine the test-retest reliability of this new protocol. The ICCs were interpreted following Landis and Koch's (1977) benchmarks of 0.00-0.20 slight, 0.21-0.40 fair, 0.41-0.60 moderate, 0.61-0.80 substantial, 0.81-1.0 almost perfect.
RESULTS: Most of the subjects reached an exercise intensity of 60-70%MVC. The general pattern of the deoxy[Hb+Mb] is that there is an increase with every increase in exercise intensity (% MVC). The population mean of the maximal increase in oxygen extraction relative to the occlusion amplitude was 44,83% and at the retest 44,6%. An ICC of r= 0,867 (p<0,0001) was found.
CONCLUSIONS: The results of the present study show that this protocol is almost perfect reliable following Landis and Koch's (1977) benchmarks and indicates it could be used to research the oxygen extraction capacity in a pathological population.