Muscle oxygenation trends after tapering in trained cyclists

BACKGROUND: This study examined muscle deoxygenation trends before and after a 7-day taper using non-invasive near infrared spectroscopy (NIRS). METHODS: Eleven cyclists performed an incremental cycle ergometer test to determine maximal oxygen consumption (VO(2)max = 4.68 ± 0.57 L·min(-1)) prior to the study, and then completed two or three high intensity (85–90% VO(2)max) taper protocols after being randomly assigned to a taper group: T30 (n = 5), T50 (n = 5), or T80 (n = 5) [30%, 50%, 80% reduction in training volume, respectively]. Physiological measurements were recorded during a simulated 20 km time trials (20TT) performed on a set of wind-loaded rollers. RESULTS AND DISCUSSION: The results showed that the physiological variables of oxygen consumption (VO(2)), carbon dioxide (VCO(2)) and heart rate (HR) were not significantly different after tapering, except for a decreased ventilatory equivalent for oxygen (V(E)/VO(2)) in T50 (p ≤ 0.05). However, during the 20TT muscle deoxygenation measured continuously in the vastus medialis was significantly lower (-749 ± 324 vs. -1140 ± 465 mV) in T50 after tapering, which was concomitant with a 4.53% improvement (p = 0.057) in 20TT performance time, and a 0.18 L·min(-1 )(4.5%) increase in VO(2). Furthermore, when changes in performance time and tissue deoxygenation (post- minus pre-taper) were plotted (n = 11), a moderately high correlation was found (r = 0.82). CONCLUSION: It was concluded that changes in simulated 20TT performance appeared to be related, in part, to changes in muscle deoxygenation following tapering, and that NIRS can be used effectively to monitor muscle deoxygenation during a taper period

Assessment of Exercise Stroke Volume and Its Prediction From Oxygen Pulse in Paralympic Athletes With Locomotor Impairments: Cardiac Long-Term Adaptations Are Possible

The determinants of cardiac output (CO) during exercise, i.e., stroke volume (SV) and heart rate (HR), could differ in Paralympic athletes (PAthl) with spinal cord injury (SCI) with respect to PAthl with locomotor impairments caused by different health conditions (HCs). The purposes of the present study were the comparisons of two groups of PAthl, one with SCI and the other with either amputation (AMP) or post poliomyelitis syndrome (PM), assessing the (1) peak cardiorespiratory responses and determinants (SV and HR) of CO during maximal and submaximal arm cranking exercise (ACE), respectively; (2) correlations between peak oxygen uptake (VO2peak) and the highest SV obtained during submaximal exercise; and (3) correlations between oxygen pulse (O-2 pulse, ratio between VO2 and HR) and both SV and O-2 arterio-venous difference [(a-v)O(2)diff]. Each athlete (19 PAthl with SCI, 9 with AMP, and 5 with PM) completed a continuous incremental cardiopulmonary ACE test to volitional fatigue to assess peak responses. In a different session, CO was indirectly measured through carbon dioxide (CO2) rebreathing method at sub-maximal exercise intensities approximating 30, 50, and 70% of the VO2peak. There were no significant differences between the PAthl groups in age, anthropometry, and VO2peak. However, peak HR was significantly lower, and peak O-2 pulse was significantly higher in PAthl with AMP/PM compared to those with SCI. During sub-maximal exercise, PAthl with AMP/PM displayed significantly higher SV values (154.8 +/- 17.60 ml) than PAthl with SCI (117.1 +/- 24.66 ml). SV correlated significantly with VO2peak in both PAthl with SCI (R-2 = 0.796) and AMP/PM (R-2 = 0.824). O-2 pulse correlated significantly with SV in both PAthl with SCI (R-2 = 0.888) and AMP/PM (R-2 = 0.932) and in the overall sample (R-2 = 0.896). No significant correlations were observed between O-2 pulse and (a-v)O(2)diff. It was concluded that in PAthl with different HCs: (1) significant differences, as a consequence of the different HC, exist in the determinants of CO at maximal and submaximal ACE; (2) SV is a significant determinant of VO2peak, suggesting cardiac adaptations possible also in PAthl with SCI; and (3) SV can be predicted from O-2 pulse measurements during submaximal exercise in both groups of PAthl

Vastus lateralis oxygenation during prolonged cycling in healthy males

This study examined the relationship between the acute cardiorespiratory and muscleoxygenation/blood volume changes during prolonged exercise. Eight healthy male volunteers (mean VO2max = 41.6 ± 2.4 ml/kg/min) performed 60 minutes submaximal cycling at 500f VO2max. Oxygen uptake (VO2) was measured by indirect spirometry, cardiac output (CO) was estimated via Portapres, and right vastus lateralis oxyhemoglobin/myoglobin (OxyHb/Mb), deoxyhemoglobin/myoglobin (DeoxyHb/Mb) and total hemoglobin/myoglobin (Total Hb/Mb) were recorded using near infrared spectroscopy. After 40 minutes of exercise, there was a significant increase in VO2 due to a significantly higher (a – v)O2diff. After 30 mins of exercise CO was unchanged, but there was a significant decrease in stroke volume and a proportionate increase in heart rate indicating the occurrence of cardiovascular drift. During the first few minutes of exercise, there was a decline in OxyHb/Mb and Total Hb/Mb while DeoxyHb/Mb remained unchanged. Thereafter OxyHb/Mb and Total Hb/Mb increased systematically until the termination of exercise while DeoxyHb/Mb declined. After 40 minutes of exercise, these changes were significantly different from the baselines values. There were no significant correlations between the changes in the NIRS variables and systemic VO2 or mixed (a – v)O2diff during exercise. These results suggest that factors other than localized changes in muscle oxygenation and blood volume account for the increased VO2 during prolonged submaximal exercise

Vastus medialis muscle oxygenation trends during a simulated 20 km cycle time trial

Contains fulltext : mmubn000001_231127758.pdf (publisher's version ) (Open Access)Promotores : G. Huizer en A. de RuijterXVI, 345 p