OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this a... more OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.z
The purpose of this study was to examine fatigue effects on symmetry and stability during a maxim... more The purpose of this study was to examine fatigue effects on symmetry and stability during a maximal effort running time-trial m). Recreational runners had continuous recordings of 3D trunk acceleration parameters (spatio-temporal, RMS vector ratio, step symmetry, and stride regularity) during the lT. Statistical analysis was carried out using generalised estimating equations (GEE) to investigate longitudinal changes (laps two to eight) compared to baseline (lap one), while statistically adjusting for running speed. Runners had significantly longer contact times (4m lap onwards), higher mediolateral root mean square (RMS) ratio (3d lap onwards), lower vertical symmetry and vertical RMS ratio (final lap). Coaches could use these results to recognize, minimize, and delay fatigue related onset of asymmetries and instabilities possibly through training strategies.
International Journal of Sports Physiology and Performance, 2020
Purpose: To provide a systematic overview of physiological parameters used to determine the train... more Purpose: To provide a systematic overview of physiological parameters used to determine the training status of a trail runner and how well these parameters correlate with real-world trail running performance. Method: An electronic literature search of the PubMed and Scopus digital databases was performed. Combinations of the terms “trail run” or “trail runner” or “trail running” and “performance” were used as search terms. Seven studies met the inclusion criteria. Results: Trail running performance most commonly correlated (mean [SD]) with maximal aerobic capacity (71%; r = −.50 [.32]), lactate threshold (57%; r = −.48 [.28]), velocity at maximal aerobic capacity (43%; r = −.68 [.08]), running economy (43%; r = −.31 [.22]), body fat percentage (43%; r = .55 [.21]), and age (43%; r = .52 [.14]). Regression analyses in 2 studies were based on a single variable predicting 48% to 60% of performance variation, whereas 5 studies included multiple variable regression analyses predicting 48...
South African Journal for Research in Sport Physical Education and Recreation, 2003
The purpose of this study was to develop a questionnaire that measures the assertiveness of netba... more The purpose of this study was to develop a questionnaire that measures the assertiveness of netball players. The identification of typical characteristics and assessment by experts regarding the correctness and technical presentation of the items resulted in a preliminary questionnaire. The item analysis for the reduction of items took place by applying the homogeneity approach and the correlation of the score of each item with the total score. Ninety-two senior netball players participated in the major phase of this study. The players completed the preliminary questionnaire on assertiveness as well as the South African Personality Questionnaire that served as criterion measure for establishing the validity of the final form of 22-items. Internal consistency reliability was determined by means of the split-half-method. Both the reliability (r = 0.834) and validity (r = 0.297; p < 0.01) of the instrument proved to be satisfactory. It was concluded that this questionnaire is suitable for use in a netball setting.
Changes in oxygen cost per a given distance of running due to fatigue have often been accompanied... more Changes in oxygen cost per a given distance of running due to fatigue have often been accompanied with alterations in running kinematics. Nevertheless, it is not certain if the changes in the oxygen cost of transport are as a result of the fatigue or the modifications in the kinematics. We, therefore, sought to understand the correlations between changes in running kinematics and oxygen cost of transport in fatigued running. Thirty-two recreational (16 men, 16 women) runners underwent a fatigue protocol which involved incremental speed to volitional exhaustion on a motorized treadmill, whiles heart rate, oxygen consumption, blood lactate, and RPE were monitored. Spatio-temporal kinematic data was assessed with an Optogait photoelectric system, and GoPro Hero 4 Black camera was used to capture upper extremity kinematics for offline analysis. Changes in pre-and post-fatigue and the interactions between the changes in kinematic parameters and oxygen cost of transport were assessed. For...
Maintaining stability under dynamic conditions is an inherent challenge to bipedal running. This ... more Maintaining stability under dynamic conditions is an inherent challenge to bipedal running. This challenge may impose an energetic cost (Ec) thus hampering endurance running performance, yet the underlying mechanisms are not clear. Wireless triaxial trunk accelerometry is a simple tool that could be used to unobtrusively evaluate these mechanisms. Here, we test a cost of instability hypothesis by examining the contribution of trunk accelerometry-based measures (triaxial root mean square, step and stride regularity, and sample entropy) to interindividual variance in Ec (J/m) during treadmill running. Accelerometry and indirect calorimetry data were collected concurrently from 30 recreational runners (16 men; 14 women) running at their highest steady-state running speed (80.65 ± 5.99% V̇o2max). After reducing dimensionality with factor analysis, the effect of dynamic stability features on Ec was evaluated using hierarchical multiple regression analysis. Three accelerometry-based measu...
OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this a... more OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.z
South African Journal for Research in Sport, Physical Education and Recreation
Please help populate SUNScholar with the full text of SU research output. Also - should you need ... more Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to scholar@sun.ac.za. Thank you.Journal Articles (subsidised)Geneeskunde en GesondheidswetenskappeFisioterapi
OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this a... more OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.z
The purpose of this study was to examine fatigue effects on symmetry and stability during a maxim... more The purpose of this study was to examine fatigue effects on symmetry and stability during a maximal effort running time-trial m). Recreational runners had continuous recordings of 3D trunk acceleration parameters (spatio-temporal, RMS vector ratio, step symmetry, and stride regularity) during the lT. Statistical analysis was carried out using generalised estimating equations (GEE) to investigate longitudinal changes (laps two to eight) compared to baseline (lap one), while statistically adjusting for running speed. Runners had significantly longer contact times (4m lap onwards), higher mediolateral root mean square (RMS) ratio (3d lap onwards), lower vertical symmetry and vertical RMS ratio (final lap). Coaches could use these results to recognize, minimize, and delay fatigue related onset of asymmetries and instabilities possibly through training strategies.
International Journal of Sports Physiology and Performance, 2020
Purpose: To provide a systematic overview of physiological parameters used to determine the train... more Purpose: To provide a systematic overview of physiological parameters used to determine the training status of a trail runner and how well these parameters correlate with real-world trail running performance. Method: An electronic literature search of the PubMed and Scopus digital databases was performed. Combinations of the terms “trail run” or “trail runner” or “trail running” and “performance” were used as search terms. Seven studies met the inclusion criteria. Results: Trail running performance most commonly correlated (mean [SD]) with maximal aerobic capacity (71%; r = −.50 [.32]), lactate threshold (57%; r = −.48 [.28]), velocity at maximal aerobic capacity (43%; r = −.68 [.08]), running economy (43%; r = −.31 [.22]), body fat percentage (43%; r = .55 [.21]), and age (43%; r = .52 [.14]). Regression analyses in 2 studies were based on a single variable predicting 48% to 60% of performance variation, whereas 5 studies included multiple variable regression analyses predicting 48...
South African Journal for Research in Sport Physical Education and Recreation, 2003
The purpose of this study was to develop a questionnaire that measures the assertiveness of netba... more The purpose of this study was to develop a questionnaire that measures the assertiveness of netball players. The identification of typical characteristics and assessment by experts regarding the correctness and technical presentation of the items resulted in a preliminary questionnaire. The item analysis for the reduction of items took place by applying the homogeneity approach and the correlation of the score of each item with the total score. Ninety-two senior netball players participated in the major phase of this study. The players completed the preliminary questionnaire on assertiveness as well as the South African Personality Questionnaire that served as criterion measure for establishing the validity of the final form of 22-items. Internal consistency reliability was determined by means of the split-half-method. Both the reliability (r = 0.834) and validity (r = 0.297; p < 0.01) of the instrument proved to be satisfactory. It was concluded that this questionnaire is suitable for use in a netball setting.
Changes in oxygen cost per a given distance of running due to fatigue have often been accompanied... more Changes in oxygen cost per a given distance of running due to fatigue have often been accompanied with alterations in running kinematics. Nevertheless, it is not certain if the changes in the oxygen cost of transport are as a result of the fatigue or the modifications in the kinematics. We, therefore, sought to understand the correlations between changes in running kinematics and oxygen cost of transport in fatigued running. Thirty-two recreational (16 men, 16 women) runners underwent a fatigue protocol which involved incremental speed to volitional exhaustion on a motorized treadmill, whiles heart rate, oxygen consumption, blood lactate, and RPE were monitored. Spatio-temporal kinematic data was assessed with an Optogait photoelectric system, and GoPro Hero 4 Black camera was used to capture upper extremity kinematics for offline analysis. Changes in pre-and post-fatigue and the interactions between the changes in kinematic parameters and oxygen cost of transport were assessed. For...
Maintaining stability under dynamic conditions is an inherent challenge to bipedal running. This ... more Maintaining stability under dynamic conditions is an inherent challenge to bipedal running. This challenge may impose an energetic cost (Ec) thus hampering endurance running performance, yet the underlying mechanisms are not clear. Wireless triaxial trunk accelerometry is a simple tool that could be used to unobtrusively evaluate these mechanisms. Here, we test a cost of instability hypothesis by examining the contribution of trunk accelerometry-based measures (triaxial root mean square, step and stride regularity, and sample entropy) to interindividual variance in Ec (J/m) during treadmill running. Accelerometry and indirect calorimetry data were collected concurrently from 30 recreational runners (16 men; 14 women) running at their highest steady-state running speed (80.65 ± 5.99% V̇o2max). After reducing dimensionality with factor analysis, the effect of dynamic stability features on Ec was evaluated using hierarchical multiple regression analysis. Three accelerometry-based measu...
OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this a... more OpvoedkundeSportwetenskapPlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: scholar@sun.ac.z
South African Journal for Research in Sport, Physical Education and Recreation
Please help populate SUNScholar with the full text of SU research output. Also - should you need ... more Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to scholar@sun.ac.za. Thank you.Journal Articles (subsidised)Geneeskunde en GesondheidswetenskappeFisioterapi
Uploads
Papers by Ranel Venter