No abstract

Purpose: Wheelchair sports have become popular in Germany. This is important because of the difficulty experienced by wheelchair-dependent people in maintaining cardiovascular health and fitness by daily activities. Increasing energy expenditure (EE; kcal h À1 ) is one of the most effective ways of decreasing risk of cardiovascular disease. The purpose of this study was to evaluate the EE of individuals with spinal cord injury in ball games for wheelchair-dependent persons. Methods: Fourteen tennis players (WT), 10 basketball players (WB) and 12 rugby players (WR) completed a basal metabolism evaluation and a training test to measure respiratory parameters. Results: In the basal metabolism test EE in WT was 66.8±12.8 kcal h À1 , in WB 62.7±15.0 kcal h À1 and in WR 63.5 ± 12.9 kcal h À1 . During training EE in WT was 325.8 ± 73.0 kcal h À1 , in WB 374.8±127.1 kcal h À1 and in WR 248.5±69.4 kcal h À1 . The average EE of the whole group was: 316.4 ± 89.6 kcal h À1 with a corresponding heart rate of 118.5 ± 23.1 b.p.m. and a lactate concentration of 2.09±0.7 mmol l À1 . Statistical analysis showed significantly lower values of EE, heart rate and oxygen uptake for the WR group in comparison to the other groups. Conclusion:The results indicate that the additional leisure time EE of persons participating in WB and WT is sufficient to maintain fitness. This level of EE is comparable to the recommendations of the ACSM for able-bodied persons, and therefore might be sufficient to prevent the development of cardiovascular diseases.

Studies have shown that, depending on intensity, endurance exercise increases neurotrophins and thereby induces neuroplasticity. However, data on the effect of acute resistance exercise at different intensities on neurotrophins is not yet available. Thus, we conducted 2 trials to determine the serum concentrations of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF-1) before and after a low or high intensity resistance exercise in 11 healthy humans. Exercise load was related to 3 repetitions of maximal effort isokinetic work involving knee extension under alternating concentric and eccentric conditions for muscle work at a velocity of 60°s-1 registered during a familiarization session. The torque angle diagrams from these 3 repetitions were averaged and displayed as target curves in the test sessions, the intensity of resistance exercise was set at 40% (trial: R1) or 110% (trial: R2) of the averaged individual maximal effort curve, respectively. After resistance exercise, serum IGF-1 was increased significantly (p<0.01) by 28% in R1 and 16% in R2 compared to pre-exercise levels. Resistance exercise did not increase serum VEGF at any time point. Serum BDNF increased during exercise compared to post-exercise, but did not achieve significant difference from pre-exercise values. The present study shows that either low or high resistance exercise increases levels of IGF-1, but not of BDNF or VEGF. This finding is of importance for health promotion by means of resistance exercise because circulating serum IGF-1 has been demonstrated to mediate positive effects of exercise on brain functions.

Handbiking as a wheelchair sport has gained increased popularity in Germany. It is an attractive sport and seems to be important for the prevention of cardiovascular diseases. For a handbike (HB), the position of the cranks can be synchronous (CS) or asynchronous (CA). The purpose of this study was to examine both forms of riding in persons with a spinal cord injury who are used to a HB. Thirty-five athletes with a spinal cord injury (32 paraplegically and 3 quadriplegically handicapped persons) from Germany agreed to participate in the present investigation. All subjects performed 2 multistage incremental exercise tests until exhaustion sitting in their own HB that was fixed to an ergometer. The tests were randomized for the crank montage. Statistical analysis revealed significantly higher maximal workload in CS compared to CA but no differences in maximal HR and LA. At defined workload intensities, we found lower VO 2 values for CS at 30, 60, and 90 W and lower HR for CS at 90 W. LA values were significantly lower for CA at 30 W and higher at 90 W, with no difference at 60 W. We therefore conclude that CS has a higher efficiency for athletes who are used to a HB.

Acute moderate exercise has been shown to induce prolonged changes in functional connectivity (FC) within affect and reward networks. The influence of different exercise intensities on FC has not yet been explored. Twenty-five male athletes underwent 30 min of “low”- (35%<lactate threshold (LT)) and “high”- (20%>LT) intensity exercise bouts on a treadmill. Resting-state fMRI was acquired at 3 Tesla before and after exercise, together with the Positive and Negative Affect Scale (PANAS). Data of 22 subjects (3 dropouts) were analyzed using the FSL feat pipeline and a seed-to-network-based analysis with the bilateral amygdala as the seed region for determining associated FC changes in the “emotional brain.” Data were analyzed using a repeated measures ANOVA. Comparisons between pre- and post-exercise were analyzed using a one-sample t-test, and a paired t-test was used for the comparison between “low” and “high” exercise conditions (nonparametric randomization approach, results reported at p<0.05). Both exercise interventions induced significant increases in the PANAS positive affect scale. There was a significant interaction effect of amygdalar FC to the right anterior insula, and this amygdalar-insular FC correlated significantly with the PANAS positive affect scale (r=0.47, p=0.048) in the “high”-intensity exercise condition. Our findings suggest that mood changes after exercise are associated with prolonged alterations in amygdalar-insular FC and occur in an exercise intensity-dependent manner.