Brandon R. Rigby

Cardiorespiratory and Biomechanical Responses to Simulated Recreational Horseback Riding in Healthy Children.

Purpose: The purpose of this study was to determine the reliability of cardiorespiratory and pelvic kinematic responses to simulated horseback riding (SHBR) and to characterize responses to SHBR relative to walking in apparently healthy children. Method: Fifteen healthy children (Mage = 9.5 ± 2.6 years) completed SHBR on a commercially available simulator at low intensity (0.27 Hz) and high intensity (0.65 Hz) during 3 sessions on different occasions. Heart rate (HR), blood pressure, and respiratory gases were measured at rest and during steady-state exercise at both intensities. Pelvic displacement was measured during steady-state exercise. Rate of energy expenditure, mean arterial pressure, and rate pressure product (RPP) were calculated. Participants also walked on a treadmill for 26.8 m/min to 80.5 m/min in 13.4-m/min increments at 0% grade during 1 session to compare cardiorespiratory responses with those of SHBR. Results: Physiological variables across all 3 SHBR sessions were similar at both intensities (p>.05 for all). Intraclass correlation coefficients (ICCs) and coefficients of variation indicate good to modest reliability of cardiorespiratory measures during SHBR (ICCs = .542–.996 for oxygen consumption, energy expenditure, and RPP). Cardiorespiratory variables, except for HR, were 2% to 19% greater, and pelvic displacement was up to 37% greater with high-intensity riding. Treadmill walking at all speeds elicited greater physiological responses compared with SHBR (p < .05). Conclusion: Cardiorespiratory responses and pelvic kinematics are reproducible with SHBR in young children, and these responses were lower than those elicited by slow treadmill walking.

Taking aim at the Müller-Lyer goalkeeper illusion: an illusion bias in action that originates from the target not being optically specified.

Van der Kamp and Masters (2008) reported that goalkeeper postures that mimic the Müller-Lyer (1889) illusion affect the location of handball penalty throws. In four experiments, we aimed to verify that the effects on throwing are consistent with an illusory bias (Experiments 1 and 2), and to examine how these observations can be understood in the context of Milner and Goodales (1995, 2008) two-visual systems model (Experiments 3 and 4). Experiments 1 and 2 confirmed that the goalkeeper Müller-Lyer posture may indeed induce an illusory bias in throwing, implying that allocentric information is used in far-aiming action tasks. Experiment 3 demonstrated that the bias was not related to a participants throwing skill. Experiment 4 suggested that an absence of visual information to instantaneously specify target location may have induced use of context-dependent allocentric information, causing the throwing bias. The results are discussed in the context of recent debates about the roles of the two-visual systems in perception and action. It is suggested that the two systems are first and foremost perceptual systems that serve the pickup of different sources of information.

Thoracic Outlet Syndrome: Biomechanical and Exercise Considerations

Thoracic outlet syndrome (TOS) describes a group of disorders that are due to a dynamic compression of blood vessels or nerves, between the clavicle and first rib or cervical vertebral nerve roots. Individuals with TOS typically experience upper limb pain, numbness, tingling, or weakness that is exacerbated by shoulder or neck movement. The causes of TOS vary, and can include abrupt movements, hypertrophy of the neck musculature, and anatomical variations in which the brachial plexus roots pass through this musculature, edema, pregnancy, repeated overhead motions, the blockage of an artery or vein, or abnormal posture. To understand the complexity of this condition, an analysis of shoulder anatomy and mechanics are needed to help describe limitations and the subsequent pathophysiology of TOS. Several treatment options are available, including surgery, medications, and exercise. A comprehensive study of shoulder anatomy and biomechanics, and knowledge of the benefits of exercise, may help clinicians and healthcare practitioners determine the most appropriate treatment plan for an individual with TOS.

Cardiorespiratory Responses During Aquatic Treadmill Exercise and Land Treadmill Exercise in Adults with Diabetes: 752 Board #68 June 1, 3: 30 PM - 5: 00 PM.

The purpose of this study was to compare the effect of aquatic treadmill (ATM) exercise to land treadmill (LTM) exercise in adults with type 2 diabetes. Five participants with type 2 diabetes (T2D group; 4 females, 1 male; age = 51±6 years; height = 170±7 cm; weight = 96±24 kg; body fat = 31.6±2.2%) and five participants without type 2 diabetes (control group; 4 females, 1 male; age = 51±6 years; height = 170±6 cm; weight = 71±15 kg; body fat = 26.8±4.6%) completed the study. Protocols for both ATM exercise and LTM exercise began at 2 mph with 0% grade and increased by 1 mph after 5 minutes at each stage. Termination occurred after participants completed the protocol or reached 85% of heart rate reserve. Heart rate, absolute and relative VO2, and systolic and diastolic blood pressure were measured at rest and during steady-state exercise at each intensity. Mean arterial pressure (MAP) was calculated. A 2 x 2 x 3 Mixed Factorial ANOVA and Bonferroni post hoc test with a significance level of .0125 were used. There was a significant difference (p<.0125) in all measures with an increase in intensity for each mode of exercise. Heart rate response was significantly different at 2 mph and 4 mph between LTM exercise and ATM exercise for those with type 2 diabetes (LTM @ 2 mph: 101±12 bpm vs. ATM @ 2 mph: 92±8 bpm, p<.0125; LTM @ 4 mph: 140±18 bpm vs. ATM @ 4 mph: 123±12 bpm, p<.0125) and those without type 2 diabetes (LTM @ 2 mph: 91±10 bpm vs. ATM @ 2 mph: 82±10 bpm, p<.0125; LTM @ 4 mph: 125±15 bpm vs. ATM @ 4 mph: 113±12 bpm, p<.0125). There was a significant difference between the relative VO2 of the two groups at 4 mph while performing the land treadmill exercise (T2D: 14.1±1.4 ml/kg/min vs. control: 18.4±1.6 ml/kg/min, p<.0125). There was no difference in absolute VO2 between participant groups or modes of exercise. Those with type 2 diabetes had an increased MAP versus those without type 2 diabetes while performing the land treadmill exercise at 2 mph (T2D: 93±3 mmHg vs. control: 81±5 mmHg, p<.0125). Although there is some evidence for the varying effects of ATM and LTM exercise when comparing those with type 2 diabetes and those without type 2 diabetes, heart rate, VO2, and MAP respond similarly in both groups during ATM and LTM exercise at most treadmill speeds.