Repeated-sprint cycling does not induce respiratory muscle fatigue in active adults: measurements from the powerbreathe® inspiratory muscle trainer.

This study examined respiratory muscle strength using the POWERbreathe® inspiratory muscle trainer (i.e., 'S-Index') before and after repeated-sprint cycling for comparison with maximal inspiratory pressure (MIP) values obtained during a Mueller maneuver. The S-Index was measured during six trials across two sessions using the POWERbreathe® and MIP was measured during three trials in a single session using a custom-made manometer in seven recreationally active adults. Global respiratory muscle strength was measured using both devices before and after the performance of sixteen, 6-s sprints on a cycle ergometer. Intraclass correlation coefficients for the POWERbreathe® S-index indicated excellent (p < 0.05) trial-to-trial (r = 0.87) and day-to-day (r = 0.90) reliability yet there was no significant correlation (r = -0.35, p = 0.43) between the S-Index measured using the POWERbreathe® and MIP measured during a Mueller maneuver. Repeated-sprint cycling had no effect on respiratory muscle strength as measured by the POWERbreathe® (p > 0.99) and during the Mueller maneuver (p > 0.99). The POWERbreathe® S-Index is a moderately reliable, but not equivalent, measure of MIP determined during a Mueller maneuver. Furthermore, repeated-sprint cycling does not induce globalized respiratory muscle fatigue in recreationally-active adults. Key pointsThe S-Index as measured by the POWERbreathe® is a reliable measure of respiratory muscle strengthThe S-Index does not accurately reflect maximal inspiratory pressure obtained from a Mueller maneuverRepeated-sprint cycling does not induce respiratory muscle fatigue as measured by the POWERbreathe® and the Manometer.

Measurement of three-dimensional cervical segmental kinematics: Reliability of whole vertebrae and facet-based approaches.

BACKGROUND: Previous studies have used orientation and translation of whole-vertebrae to describe three-dimensional cervical segmental kinematics. Describing kinematics using facet joint movement may be more relevant to pathology and effects of interventions but has not been investigated in the cervical spine. This study compared the reliability of two different methods (whole-vertebrae vs facet joint) to evaluate cervical kinematics. METHODS: Two healthy adults each had six cervical (C1 to T1) magnetic resonance imaging scans, two each in neutral and left and right rotation. A semi-automated method of segmentation and alignment determined the relative orientation and translation of each whole-vertebrae and translation of each facet joint. Intra-rater and inter-rater reliability was determined using limits of agreement (LOA) with 95% confidence intervals and intraclass correlation coefficients (ICC3,1 for intra- and ICC2,1 for inter-rater). RESULTS: The LOA for intra-rater evaluation of facet movement was superior to whole vertebra translation. Both methods showed excellent intra-rater ICC3,1 (0.80-0.99) and inter-rater ICC2,1 (0.79-0.85) for all variables except for Euler angle for flexion/extension which was good (0.65). Intra-and inter-rater ICCs were better for facet movement than all measures of whole of vertebrae movement except Euler angles of axial rotation where no difference was detected. CONCLUSIONS: Measurement of three-dimensional segmental kinematics using either the facet joint or the whole-vertebrae method demonstrated excellent and comparable reliability. These findings support the use of the facet joint method as an option for describing and investigating cervical segmental kinematics.

Anaerobic Energy Production During Sprint Paddling in Junior Competitive and Recreational Surfers.

This study compared determinants of a 30-s all-out paddling effort (30-s sprint-paddling test) between junior surfboard riders (surfers) of varying ability. Eight competitive (COMP) and 8 recreational (REC) junior male surfers performed a 30-s sprint-paddling test for the determination of peak sprint power and accumulated O2 deficit. Surfers also performed an incremental-paddling test for the determination of the O2 uptake-power output relationship that was subsequently used to calculate the accumulated O2 deficit for the 30-s sprint-paddling test. During the 30-s sprint-paddling test, peak sprint power (404 ± 98 vs 292 ± 56 W, respectively, P = .01) and the accumulated O2 deficit (1.60 ± 0.31 vs 1.14 ± 0.38 L, respectively, P = .02) were greater in COMP than in REC surfers, whereas peak O2 uptake measured during the incremental-paddling test was not different (2.7 ± 0.1 vs 2.5 ± 0.2 L/min, respectively, P = .11). The higher peak sprint power and larger accumulated O2 deficit observed in COMP than in REC surfers during a 30-s sprint paddling test suggest that surfing promotes development of the anaerobic energy systems. Furthermore, peak sprint power determined during 30 s of sprint paddling may be considered a sensitive measure of surfing ability or experience in junior male surfers.