Physiological determinants of climbing-specific finger endurance and sport rock climbing performance

Abstract

The aim of the study was to examine several physiological responses to a climbing-specific task to identify determinants of endurance in sport rock climbing. Finger strength and endurance of intermediate rock climbers (n = 11) and non-climbers (n = 9) were compared using climbing-specific apparatus. After maximum voluntary contraction (MVC) trials, two isometric endurance tests were performed at 40% (s = 2.5%) MVC until volitional exhaustion (continuous contractions and intermittent contractions of 10 s, with 3 s rest between contractions). Changes in muscle blood oxygenation and muscle blood volume were recorded in the flexor digitorum superficialis using near infra-red spectroscopy. Statistical significance was set at P < 0.05. Climbers had a higher mean MVC (climbers: 485 N, s = 65; non-climbers 375 N, s = 91) (P = 0.009). The group mean endurance test times were similar. The force – time integral, used as a measure of climbing-specific endurance, was greater for climbers in the intermittent test (climbers: 51,769 N · s, s = 12,229; non-climbers: 35,325 N · s, s = 9724) but not in the continuous test (climbers: 21,043 N · s, s = 4474; non-climbers: 15,816 N · s, s = 6263). Recovery of forearm oxygenation during rest phases (intermittent test) explained 41.1% of the variability in the force – time integral. Change in total haemoglobin was significantly greater in non-climbers (continuous test) than climbers (P = 0.023 – 40% test timepoint, P = 0.014 – 60% test timepoint). Pressor responses were similar between groups and not related to the force – time integral for either test. We conclude that muscle re-oxygenation during rest phases is a predictor of endurance performance.     

Child care and family processes: Bi-directional relations between child care quality,home environments,and maternal depression

The current study examined whether within-family changes in child care quality and quantity predicted subsequent changes in home environment quality and maternal depression across early childhood (6 to 54 months of age). Data were drawn from the NICHD Study of Early Child Care and Youth Development (n = 1239; 77% White; 48% female; data collection from 1991 to 1996), and were analyzed using Random Intercept Cross-Lagged Panel Models. Within-family increases in child care quality predicted modest increases in home environment quality (β = .13–.17). These effects were most robust from child age 6 to 15 months. Increases in child care quality produced small, statistically non-significant, reductions in depression. Time-specific increases in child care quantity were not consistently predictive of either outcome.     

Determining the Overall Impact of Interruptions During Online Testing

With an increase in the number of online tests, interruptions during testing due to unexpected technical issues seem unavoidable. For example, interruptions occurred during several recent state tests. When interruptions occur, it is important to determine the extent of their impact on the examinees’ scores. There is a lack of research on this topic due to the novelty of the problem. This article is an attempt to fill that void. Several methods, primarily based on propensity score matching, linear regression, and item response theory, were suggested to determine the overall impact of the interruptions on the examinees’ scores. A realistic simulation study shows that the suggested methods have satisfactory Type I error rate and power. Then the methods were applied to data from the Indiana Statewide Testing for Educational Progress‐Plus (ISTEP+) test that experienced interruptions in 2013. The results indicate that the interruptions did not have a significant overall impact on the student scores for the ISTEP+ test.