Brain function during central fatigue induced by intermittent high-intensity cycling.

BACKGROUND: The central governor model putatively explains the mechanism of endurance exercise-induced central fatigue, however high-intensity exercise-induced central fatigue strategies have not been investigated yet. This study aimed to examine how central fatigue affects neural response alterations, as measured by electroencephalographic (EEG) recordings, in intermittent high-intensity cycling. METHODS: Neural responses were assessed by measuring the alteration of brainwaves based on spectral energy band estimates during an intermittent, high-intensity, 60-min exercise bout on a cycle ergometer. The cycle ergometer incline was changed every 10 min in an intermittent pattern (10-20-5-20-5-10°). EEG was used to analyze altering brain function. Heart rate (HR), blood lactate (BL), and rating of perceived exertion (RPE) were measured after the participants completed each change in incline. RESULTS: The results showed that HR, BL, and RPE increased at an incline of 20° in comparison to a 5° incline. The spectral power of EEG was significantly increased (P Ë‚ 0.01) in the alpha and beta frequency ranges with a change in inclines between 5 and 20°. The spectral power of the EEG was significantly increased (P Ë‚ 0.01) over the whole frequency range from rest (theta + 251%, alpha + 165%, beta + 145%). CONCLUSION: Higher, relative intensities (10 and 20°) increased brain function, regardless of fatigue occurrence. HIIT (high-intensity interval training) led to an alteration in the neural response. Further work investigating the usefulness of HIIT to improve brain function is warranted.

Adding vibration to high-intensity intervals increase time at high oxygen uptake in well-trained cyclists.

The importance of accumulated time ≥90% of maximal oxygen consumption (VO2max ) to improve performance in well-trained endurance athletes is well established. The present study compared the acute effects of adding vibrations (VIB; 40 Hz) with the work intervals during a high-intensity cycling session (HIT) with a traditional HIT session without vibration (TRAD) on time ≥90% of VO2max , time ≥90% of peak heart rate (HRpeak ), electromyography (EMG) activity, and mean power in well-trained cyclists (n = 10, VO2max =78.6 ± 7.4 mL/min/kg). The order of VIB and TRAD was randomized and consisted of 6 × 5-minutes work intervals performed with the highest possible mean power across the work intervals (2.5-minutes standardized relief periods). VIB was superior to TRAD on time ≥90% of VO2max , (10.99 ± 7.00 vs 6.95 ± 5.28 minutes, respectively), time ≥90% of HRpeak (24.61 ± 2.38 vs 19.97 ± 4.12 minutes, respectively), and averaged EMG activity in m. Vastus Lateralis during the work intervals (all P < 0.05). The EMG/power output ratio across all work intervals was higher in VIB than TRAD (P < 0.05). Mean values across work intervals showed no difference between VIB and TRAD in mean power, rate of perceived exertion, or blood lactate concentration. Thus, the present study indicated that adding vibration to the work intervals during a HIT session can acutely increase the physiological responses of the cardiovascular system and increase time ≥90% VO2max and should therefore be considered in order to optimize the exercise stimulus of well-trained cyclists.

Effects of self-paced interval and continuous training on health markers in women.

PURPOSE: To compare the effects of self-paced high-intensity interval and continuous cycle training on health markers in premenopausal women. METHODS: Forty-five inactive females were randomised to a high-intensity interval training (HIIT; n = 15), continuous training (CT; n = 15) or an inactive control (CON; n = 15) group. HIIT performed 5 × 5 min sets comprising repetitions of 30-s low-, 20-s moderate- and 10-s high-intensity cycling with 2 min rest between sets. CT completed 50 min of continuous cycling. Training was completed self-paced, 3 times weekly for 12 weeks. RESULTS: Peak oxygen uptake (16 ± 8 and 21 ± 12%), resting heart rate (HR) (-5 ± 9 and -4 ± 7 bpm) and visual and verbal learning improved following HIIT and CT compared to CON (P < 0.05). Total body mass (-0.7 ± 1.4 kg), submaximal walking HR (-3 ± 4 bpm) and verbal memory were enhanced following HIIT (P < 0.05), whereas mental well-being, systolic (-5 ± 6 mmHg) and mean arterial (-3 ± 5 mmHg) blood pressures were improved following CT (P < 0.05). Participants reported similar levels of enjoyment following HIIT and CT, and there were no changes in fasting serum lipids, fasting blood [glucose] or [glucose] during an oral glucose tolerance test following either HIIT or CT (P > 0.05). No outcome variable changed in the CON group (P > 0.05). CONCLUSIONS: Twelve weeks of self-paced HIIT and CT were similarly effective at improving cardiorespiratory fitness, resting HR and cognitive function in inactive premenopausal women, whereas blood pressure, submaximal HR, well-being and body mass adaptations were training-type-specific. Both training methods improved established health markers, but the adaptations to HIIT were evoked for a lower time commitment.

[Efficacy of Home-Based Exercise Training and Adherence to Therapy in Patients After Coronary Artery Bypass Grafting].

AIM: to assess efficacy of home-based exercise training (HBET) at outpatient stage of cardiac rehabilitation and its impact on adherence to treatment in patients after coronary artery bypass grafting (CABG). MATERIAL AND METHODS: In 1 month after CABG 112 male patients (after completion of rehabilitation program in the sanatorium) were distributed to 3 groups with comparable demographic, clinical, and functional parameters: group 1 - patients fulfilling supervised cycling training program (SCTP), group 2 - patients subjected to home-based exercise training (HBET) with defined walking sessions (WS), and the control group of usual care without exercise training. Patients were examined 1, 4 months and 1 year after CABG. RESULTS: Three months SCTP was most efficient relative to improvement of exercise tolerance (ET), modification of cardiovascular risk factors (smoking, obesity, dyslipidemia), and of adherence to medical therapy. Lowest ET and worst adherence to medical and non-medical therapies were found in the group of usual care without exercise training. The intermediate position was occupied by patients subjected to HBET and WS. Effects of 3 months of HBET diminished by 1 year of follow-up. CONCLUSION: HBET of moderate intensity appeared to be safe, easily workable and affordable training program for patients after CABG. However, it was less effective, compared with SCTP. Moreover, effects of this rehabilitation program were transitory.

Aerobic training enhances muscle deoxygenation in early post-myocardial infarction.

PURPOSE: Exercise-induced skeletal muscle deoxygenation is startling by its absence in early post-myocardial infarction (MI) patients. Exercise training early post-MI is associated with reduced cardiovascular risk and increased aerobic capacity. We therefore investigated whether aerobic training could enhance the muscle deoxygenation in early post-MI patients. METHODS: 21 ± 8 days after the first MI patients (n = 16) were divided into 12-week aerobic training (TR, n = 10) or non-training (CON, n = 6) groups. Before and after intervention, patients performed ramp bicycle exercise until exhaustion. Muscle deoxygenation was measured at vastus lateralis by near-infrared spectroscopy during exercise. RESULTS: Aerobic training significantly increased peak oxygen uptake (VO2) (18.1 ± 3.0 vs. 22.9 ± 2.8 mL/kg/min), decreased the change in muscle oxygen saturation from rest to submaximal and peak exercise (∆SmO2; 2.4 ± 5.7 vs. -7.0 ± 3.4 %), and increased the relative change in deoxygenated hemoglobin/myoglobin concentration from rest to submaximal (-1.5 ± 2.3 vs. 3.0 ± 3.6 µmol/L) and peak exercise (1.1 ± 4.5 vs. 8.2 ± 3.5 µmol/L). Change in total hemoglobin/myoglobin concentration in muscle was not significantly affected by training. In CON, no significant alterations were found after 12 weeks in either muscle deoxygenation or peak VO2 (18.6 ± 3.8 vs. 18.9 ± 4.6 mL/kg/min). An increase in peak VO2 was significantly negatively correlated with change in ∆SmO2 (r = -0.65) and positively associated with change in ∆deoxy-Hb/Mb at peak exercise (r = 0.64) in TR. CONCLUSIONS: In early post-MI patients, aerobic training enhanced skeletal muscle deoxygenation, and the enhancement was related to increased aerobic capacity.

Effects of Low Volume Aerobic Training on Muscle Desaturation During Exercise in Elderly Subjects.

Aging enhances muscle desaturation responses due to reduced O2 supply. Even though aerobic training enhances muscle desaturation responses in young subjects, it is unclear whether the same is true in elderly subjects. Ten elderly women (age: 62±4 years) participated in 12-weeks of cycling exercise training. Training consisted of 30 min cycling exercise at the lactate threshold. The subjects exercised 15±6 sessions during training. Before and after endurance training, the subjects performed ramp cycling exercise. Muscle O2 saturation (SmO2) was measured at the vastus lateralis by near infrared spectroscopy during the exercise. There were no significant differences in SmO2 between before and after training. Nevertheless, changes in peak pulmonary O2 uptake were significantly negatively related to changes in SmO2 (r=-0.67, p<0.05) after training. Muscle desaturation was not enhanced by low volume aerobic training in this study, possibly because the training volume was too low. However, our findings suggest that aerobic training may potentially enhance muscle desaturation at peak exercise in elderly subjects.

Low Volume Aerobic Training Heightens Muscle Deoxygenation in Early Post-Angina Pectoris Patients.

The aim of this study was to investigate the effect of low volume aerobic exercise training on muscle O2 dynamics during exercise in early post-angina pectoris (AP) patients, as a pilot study. Seven AP patients (age: 72 ± 6 years) participated in aerobic exercise training for 12 weeks. Training consisted of continuous cycling exercise for 30 min at the individual's estimated lactate threshold, and the subjects trained for 15 ± 5 exercise sessions over 12 weeks. Before and after training, the subjects performed ramp cycling exercise until exhaustion. Muscle O2 saturation (SmO2) and relative changes from rest in deoxygenated hemoglobin concentration (∆Deoxy-Hb) and total hemoglobin concentration (∆Total-Hb) were monitored at the vastus lateralis by near infrared spatial resolved spectroscopy during exercise. The SmO2 was significantly lower and ∆Deoxy-Hb was significantly higher after training than before training, while there were no significant changes in ∆Total-Hb. These results indicated that muscle deoxygenation and muscle O2 extraction were potentially heightened by aerobic exercise training in AP patients, even though the exercise training volume was low.

Measurement of non-invasive cardiac output during cycling exercise in ischemic stroke inpatients: A pilot study.

BACKGROUND: Cardiac dysfunction accompanies acute ischemic stroke and affects the effective implementation of early rehabilitation interventions. There is a lack of reference hemodynamic data on cardiac function in the subacute phase of ischemic stroke. OBJECTIVE: In this study, we aimed to identify appropriate cardiac parameters for exercise training utilizing a pilot study. METHODS: We used a transthoracic electrical bioimpedance non-invasive cardiac output measurement (NICOM) device to monitor cardiac function in real time for two groups [i.e., subacute ischemic stroke inpatients group (n= 10) and healthy control group (n= 11)] using a cycling exercise experiment. The parameters of both groups were compared to highlight the cardiac dysfunction in the subacute phase in patients with ischemic stroke. RESULTS: We considered stroke volume index (SVI) and systemic vascular resistance index (SVRi) as the primary outcomes, and there was significant intragroup difference (stroke group: P< 0.001; control group: P< 0.001, using one-way ANOVA) and significant intergroup difference at each individual time segment (P< 0.01, using independent t-test). Among the secondary outcomes, i.e., cardiac index (CI), ejection fraction (EF), end-diastolic volume (EDV), and cardiac contraction index (CTI), we found significant intergroup differences in CI, EF, and CTI scores (P< 0.01, using independent t-test). Significant interaction with respect to time and group were seen only in the SVRi and CI scores (P< 0.01, using two-way ANOVA). There was no significant inter- or intra-group differences in EDV scores. CONCLUSION: SVRI, SVI, and CI values highlight cardiac dysfunction in stroke patients the most. At the same time, these parameters suggest that cardiac dysfunction in stroke patients may be closely related to the increased peripheral vascular resistance caused by infarction and the limitation of myocardial systolic function.

Does Cycling Training Reduce Quality of Functional Movement Motor Patterns and Dynamic Postural Control in Adolescent Cyclists? A Pilot Study.

The aim of this study was to assess whether cycling training may influence quality of functional movement patterns and dynamic postural control. We also sought to determine if the Functional Movement Screen and Lower Quarter Y-balance tests could be predictive of injury risk among adolescent road cyclists. Twenty-three male road cyclists, aged 15-18 years, were involved in the study. Quality of functional movement patterns was assessed using the Functional Movement Screen test (FMS). Dynamic postural control was evaluated using the Lower Quarter Y-balance test (YBT-LQ). Information on injury occurrence was collected through a retrospective survey. The results showed the highest percentage of scores equalling 0 and 1 (>30% in total) in two FMS component tests: the hurdle step and trunk stability push-up. The results also demonstrated a low injury predictive value of the Functional Movement Screen (cut-off <14/21 composite score) and the Lower Quarter Y-balance test (cut-off <94% composite score and >4 cm reach distance asymmetry) in adolescent road cyclists. The most important information obtained from this study is that youth road cyclists may have functional deficits within the lumbo-pelvic-hip complex and the trunk, while neither the FMS nor the YBT-LQ test are not recommended for injury risk screening in cyclists.

Variability in Submaximal Self-Paced Exercise Bouts of Different Intensity and Duration.

PURPOSE: Rating of perceived exertion (RPE) as a training-intensity prescription has been extensively used by athletes and coaches. However, individual variability in the physiological response to exercise prescribed using RPE has not been investigated. METHODS: Twenty well-trained competitive cyclists (male = 18, female = 2, maximum oxygen consumption = 55.07 [11.06] mL·kg-1·min-1) completed 3 exercise trials each consisting of 9 randomized self-paced exercise bouts of either 1, 4, or 8 minutes at RPEs of 9, 13, and 17. Within-athlete variability (WAV) and between-athletes variability (BAV) in power and physiological responses were calculated using the coefficient of variation. Total variability was calculated as the ratio of WAV to BAV. RESULTS: Increased RPEs were associated with higher power, heart rate, work, volume of expired oxygen (VO2), volume of expired carbon dioxide (VCO2), minute ventilation (VE), deoxyhemoglobin (ΔHHb) (P < .001), and lower tissue saturation index (ΔTSI%) and ΔO2Hb (oxyhaemoglobin; P < .001). At an RPE of 9, shorter durations resulted in lower VO2 (P < .05) and decreased ΔTSI%, and the ΔHHb increased as the duration increased (P < .05). At an RPE of 13, shorter durations resulted in lower VO2, VE, and percentage of maximum oxygen consumption (P < .001), as well as higher power, heart rate, ΔHHb (P < .001), and ΔTSI% (P < .05). At an RPE of 17, power (P < .001) and ΔTSI% (P < .05) increased as duration decreased. As intensity and duration increased, WAV and BAV in power, work, heart rate, VO2, VCO2, and VE decreased, and WAV and BAV in near-infrared spectroscopy increased. CONCLUSIONS: Self-paced intensity prescriptions of high effort and long duration result in the greatest consistency on both a within- and between-athletes basis.

Effect of visual biofeedback cycling training on gait in patients with multiple sclerosis. / Efectos del entrenamiento en bicicleta con retroalimentación visual sobre la marcha en pacientes con esclerosis múltiple.

INTRODUCTION: Gait alterations are present in a high percentage of patients with multiple sclerosis (MS). They appear from early stages of the disease and can limit patients' capacity to perform basic activities of daily living, affecting their quality of life. Visual biofeedback cycling training appears to be a useful tool in treating these impairments. This study aims to evaluate the short-term effect of visual biofeedback cycling training on gait in patients with MS. MATERIAL AND METHODS: A total of 61 patients with mild to moderate MS were randomly assigned to a control group and an intervention group. The intervention group received visual biofeedback cycling training (MOTOmed viva2 system) once per week for 3 months, and a home exercise program. The control group only received the home exercise program. Both groups were evaluated using the GAITRite® Walkway gait assessment system before the intervention, during the first month of the programme, and after the intervention. RESULTS: In the intervention group, the analysis revealed statistically significant differences between Functional Ambulation Profile (FAP) scores before and during the intervention (P=.014), and before and after the intervention (P=.002). A statistically significant improvement was observed in step length in the intervention group between pre- and post-intervention scores (P=.001) and between first-month and post-intervention scores (P=.004). CONCLUSIONS: Visual biofeedback cycling training improved specific gait parameters in the short term and appears to be a therapeutic option for gait retraining in patients with MS.

On the use of naturalistic methods to examine safety-relevant behaviours amongst children and evaluate a cycling education program.

School-based cycling education programs aim to improve cycling safety and participation amongst children. Available research suggests that typical programs, which focus on bicycle manoeuvring skills, have limited effects on behaviour observed on a track or planned route. The current study uses theoretically more valid, naturalistic cycling data, to evaluate Safe Cycle, a program that incorporates hazard and self-awareness training. Soon after Safe Cycle was delivered at treatment schools, research bicycles instrumented with a rearward- and a forward-facing camera were loaned to six children from treatment schools and six children from (waitlist) control schools. In each group half the children were in Year 6, and half were in Year 7/8. Each child was instructed to ride the research bicycle instead of their own bicycle for the 1-2 weeks that they had a research bicycle. Video data were reduced using a purpose-designed coding scheme that identified whether participants performed specific safety-relevant behaviours in appropriate circumstances. While the participants controlled their bicycles well, gave way appropriately to traffic at intersections, and stopped at red lights, participants frequently removed one or both hands from the handlebars, and seldom signalled turns, conducted over-shoulder-checks when changing lanes, or looked in multiple directions at intersections (except when crossing a road). While aspects of design and small sample sizes limited evaluation findings, this research demonstrated the feasibility and potential of naturalistic data to support cycling education program evaluation. Further, the study substantially extended available naturalistic study of children's cycling behaviour to highlight behaviours which might be targeted by cycling safety initiatives.

Effect of biofeedback cycling training on functional recovery and walking ability of lower extremity in patients with stroke.

This study aimed to investigate the effectiveness of biofeedback cycling training on lower limb functional recovery, walking endurance, and walking speed for patients with chronic stroke. Thirty-one patients with stroke (stroke onset >3 months) were randomly assigned into two groups using a crossover design. One group (N = 16; mean: 53.6 ± 10.3 years) underwent conventional rehabilitation and cycling training (30 minutes/time, 5 times per week for 4 weeks), followed by only conventional rehabilitation for another 4 weeks. The other group (N = 15; mean: 54.5 ± 8.0 years) underwent the same training in reverse order. The bike used in this biofeedback cycling training was the MOTOmed viva2 Movement Trainer. Outcome measures included the lower extremity subscale of Fugl-Meyer assessment (LE-FMA), the 6-minute walk test (6MWT), the 10-meter walk test (10MWT), and the modified Ashworth scale (MAS). All participants were assessed at the beginning of the study, at the end of the 4(th) week, and at the end of the 8(th) week. Thirty participants completed the study, including the cycling training interventions and all assessments. The results showed that improvements in the period with cycling training were significantly better than the noncycling period in the LE-FMA (p < 0.05), 6MWT (p < 0.001), 10MWT (p < 0.001), and MAS (p < 0.001) scores. No significant carryover effects were observed. The improvements on outcome measures were significantly different between the cycling period and the noncycling period after adjusting for potential confounding factors in the multivariate analysis of variance (p < 0.001). The study result indicates that the additional 4-week biofeedback cycling training could lead to improved LE functional recovery, walking endurance, and speed for patients with chronic stroke.