Biomedical subjects

H Groeller

Publications and source records attributed to H Groeller.

3 recordsLinked to original sources

PubMed2000

Does fatigue induced by repeated dynamic efforts affect hamstring muscle function?

PURPOSE: The purpose of this study was to determine the effects of hamstring fatigue induced by repeated maximal efforts on hamstring muscle function during maximal sprint running. METHODS: Twelve subjects performed three maximal 40-m sprints during which time high-speed film of the subjects' sprint action and EMG of five lower extremity muscles were recorded (nonfatigued condition, NFC). Subjects then performed specific and general hamstring fatigue tasks followed by three final 40-m sprints (fatigued condition, FC) during which time high-speed film and EMG of the same muscles were again recorded. RESULTS: Statistical analysis of the kinematic data indicated the following significant (P < 0.05) changes in the subjects' running action from the NFC to the FC: decreased hip and knee flexion at maximum knee extension in the swing phase of the sprint cycle, decreased leg angular velocity immediately before foot-ground contact (FGC), and decreased angular displacement of the trunk, thigh, and leg segments during the late swing phase. Statistical analysis of the EMG data indicated a significant increase in the duration of hamstring activity and earlier cessation of rectus femoris activity during the swing phase of the sprint stride. CONCLUSIONS: It was concluded that these changes in the kinematic and EMG parameters of sprint running primarily served as protective mechanisms to reduce stress placed on the hamstring muscles at critical phases of the stride cycle.

Adult↗

PubMed2000

Carotid baroreflex control of heart rate and blood pressure during ES leg cycling in paraplegics.

This study investigated control of heart rate (HR) and mean arterial pressure (MAP) at rest and during electrical stimulation (ES) leg cycling exercise (LCE) in paraplegics (Para). Seven men with complete spinal lesions (T(5)-T(11)) and six able-bodied (AB) men participated in this study. Beat-to-beat changes in HR and MAP were recorded during carotid sinus perturbation. Carotid baroreflex function curves were derived at rest and during ES-LCE for Para and during voluntary cycling (Vol) for AB. From rest to ES-LCE, oxygen uptake (VO(2)) increased (by 0.43 l/min) and HR rose (by 11 beats/min), yet MAP remained unchanged. In AB, Vol increased VO(2) (by 0.53 l/min), HR (by 22 beats/min), and MAP (by 8 mmHg). ES-LCE did not alter the carotid sinus pressure (CSP)-MAP relationship, but it displaced the CSP-HR relationship upward relative to rest. No rightward shift was observed during ES-LCE. Vol by AB produced an upward and rightward displacement of the CSP-MAP and CSP-HR relationships relative to rest. These findings suggested that the carotid sinus baroreflex was not reset during ES-LCE in Para.

Adult↗

PubMed1997

Parkinson's disease: an investigation of exercise capacity, respiratory function, and gait.

OBJECTIVE: To evaluate the exercise capacity of subjects with mild to moderate Parkinson's disease and determine whether abnormalities in respiratory function and gait affect exercise capacity. DESIGN: Descriptive. Subjects were categorized according to exercise history, disease severity, and presence/absence of upper airway obstruction. SUBJECTS AND SETTING: Sixteen volunteers with mild to moderate idiopathic Parkinson's disease attended a university research laboratory. MAIN OUTCOME MEASURES: Subjects performed a maximum exercise test on a cycle ergometer, together with respiratory function tests and a walking test. Peak values for oxygen consumption and work rate were recorded for the maximum exercise test. Measures of respiratory function included spirometry, flow-volume loops, lung volumes, and mouth pressures. Velocity, stride length, and cadence were measured for preferred and fast speeds of walking. The values obtained on each of these tests were compared with published predicted age- and gender-matched normal values. RESULTS: Peak oxygen consumptions and peak work loads achieved by subjects with Parkinson's disease were not significantly different from normal values, despite evidence of respiratory and gait abnormalities typical of Parkinson's disease. Exercise category was significantly correlated with percent predicted VO2peak (r = .64, p < .01), with sedentary subjects producing lower scores than exercising subjects. There was no significant correlation between disease severity and percent predicted VO2peak. CONCLUSION: Despite their neurological deficit, individuals with mild to moderate Parkinson's disease have the potential to maintain normal exercise capacity with regular aerobic exercise.

Airway Obstruction↗