Medicine and Science in Sports and Exercise, Oct 1, 1987
Fourteen well-trained speed skaters performed all-out exercise tests during ice speed skating, lo... more Fourteen well-trained speed skaters performed all-out exercise tests during ice speed skating, low walking (walking-like movement in skating position), and dry skating (side to side deep sitting push-offs). These dry land training activities, widely used by speed skaters during the summer period, are compared to speed skating in relation to the concept of training specificity. Relevant physiological and biomechanical variables (derived from film and video analysis) were measured. The maximal oxygen uptake achieved in low walking (60.0 +/- 5.8 ml.kg-1.min-1) was not significantly different to that achieved during speed skating (62.1 +/- 6.9), but the maximal level attained in dry skating (48.4 +/- 5.5) was significantly less than both of these. The biomechanical differences measured are substantial. The forward directed push-off, the more dynamic movement pattern in hip and knee joints, and the use of plantar flexors during low walking are essentially different from speed skating. In dry skating, a more convulsive movement pattern due to the fixed push-off position compared to speed skating was found. The consequences of the typical skating position on the physiological responses is discussed. It is concluded that neither low walking nor dry skating can be considered as specific training activities for speed skaters.
Modified gradient-echo MR techniques were applied to study the effects of inflow on functional br... more Modified gradient-echo MR techniques were applied to study the effects of inflow on functional brain imaging studies using visual and motor cortex stimulation. The results demonstrate that the large signal changes, seen in previously reported gradient-echo studies at 1.5-2.0 T, are dominated by direct inflow effects, in particular when using a large flip angle and a thin slice. The findings suggest that inflow-based functional imaging, along with Blood Oxygenation Level Dependent (BOLD) functional MRI, may play an important role in future research towards the functional organization of the human brain.
The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) ... more The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) problems as a function of carbohydrate-rich (CHO) supplements and mode of exercise. The relationship between GI problems and a variety of physiological and personal factors (age, exercise experience) was also examined. Thirty-two male tri-athletes performed three experimental trials at 1-wk intervals, each trial on a different supplement: a conventional, semisolid supplement (S; 1.2 g CHO, 0.1 g protein, and 0.02 g fat.kg BW-1 x h-1); an almost isocaloric fluid supplement (F; 1.3 g CHO.kg BW-1 x h-1, no fat, no protein); and a fluid placebo (P). The 3 h of exercise started at 75% VO2max and consisted of alternately cycling (bouts 1 and 3) and running (bouts 2 and 4). GI symptoms were monitored by a questionnaire. Analysis of variance revealed that nausea lasted longer with P as compared with S (P < 0.05). Bloating lasted longer during bout 3 with P as compared with F and S (P < 0.05). Accounting for confounding factors, most GI symptoms occurred more frequently and lasted longer during running than during cycling. Multiple regression analysis revealed significant relationships between nausea and urge to defecate, between an urge to defecate, GI cramps and flatulence, and between belching and side ache. From all other factors energy depletion, CHO malabsorption, exercise intensity, exercise experience, and age were significantly related to GI symptoms during the exercise.
Medicine and Science in Sports and Exercise, Oct 1, 1987
Fourteen well-trained speed skaters performed all-out exercise tests during ice speed skating, lo... more Fourteen well-trained speed skaters performed all-out exercise tests during ice speed skating, low walking (walking-like movement in skating position), and dry skating (side to side deep sitting push-offs). These dry land training activities, widely used by speed skaters during the summer period, are compared to speed skating in relation to the concept of training specificity. Relevant physiological and biomechanical variables (derived from film and video analysis) were measured. The maximal oxygen uptake achieved in low walking (60.0 +/- 5.8 ml.kg-1.min-1) was not significantly different to that achieved during speed skating (62.1 +/- 6.9), but the maximal level attained in dry skating (48.4 +/- 5.5) was significantly less than both of these. The biomechanical differences measured are substantial. The forward directed push-off, the more dynamic movement pattern in hip and knee joints, and the use of plantar flexors during low walking are essentially different from speed skating. In dry skating, a more convulsive movement pattern due to the fixed push-off position compared to speed skating was found. The consequences of the typical skating position on the physiological responses is discussed. It is concluded that neither low walking nor dry skating can be considered as specific training activities for speed skaters.
Modified gradient-echo MR techniques were applied to study the effects of inflow on functional br... more Modified gradient-echo MR techniques were applied to study the effects of inflow on functional brain imaging studies using visual and motor cortex stimulation. The results demonstrate that the large signal changes, seen in previously reported gradient-echo studies at 1.5-2.0 T, are dominated by direct inflow effects, in particular when using a large flip angle and a thin slice. The findings suggest that inflow-based functional imaging, along with Blood Oxygenation Level Dependent (BOLD) functional MRI, may play an important role in future research towards the functional organization of the human brain.
The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) ... more The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) problems as a function of carbohydrate-rich (CHO) supplements and mode of exercise. The relationship between GI problems and a variety of physiological and personal factors (age, exercise experience) was also examined. Thirty-two male tri-athletes performed three experimental trials at 1-wk intervals, each trial on a different supplement: a conventional, semisolid supplement (S; 1.2 g CHO, 0.1 g protein, and 0.02 g fat.kg BW-1 x h-1); an almost isocaloric fluid supplement (F; 1.3 g CHO.kg BW-1 x h-1, no fat, no protein); and a fluid placebo (P). The 3 h of exercise started at 75% VO2max and consisted of alternately cycling (bouts 1 and 3) and running (bouts 2 and 4). GI symptoms were monitored by a questionnaire. Analysis of variance revealed that nausea lasted longer with P as compared with S (P < 0.05). Bloating lasted longer during bout 3 with P as compared with F and S (P < 0.05). Accounting for confounding factors, most GI symptoms occurred more frequently and lasted longer during running than during cycling. Multiple regression analysis revealed significant relationships between nausea and urge to defecate, between an urge to defecate, GI cramps and flatulence, and between belching and side ache. From all other factors energy depletion, CHO malabsorption, exercise intensity, exercise experience, and age were significantly related to GI symptoms during the exercise.
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