ABSTRACT
Duplicate haemoglobin mass (Hbmass) measurements are recommended before and after altitude training sojourns to identify individual adaptations in athletes with a high level of certainty. Duplicate measurements reduce typical error (TE) and disclose measurement outliers, but are usually made on separate days, which is not a practical protocol for routine services in elite sport settings. The aim of this study was therefore to investigate whether it is safe (carboxyhaemoglobin<10%) to measure Hbmass twice on the same day and to compare TE with measurements made on separate days. 18 healthy men completed 3 different procedures to measure Hbmass twice a day with the carbon monoxide rebreathing method: A (Hbmass measured twice within 6 h), B (dito A, combined with 1 h of hyperoxic training between the tests), C (dito B, within 2 h). First Hbmass measurements of the 3 test days served as procedure D. Carboxyhaemoglobin did not exceed 10% in any procedure. TE and confidence limits for procedures A, B, C and D were 1.4% (1.0-2.1%), 1.1% (0.8-1.7%), 1.3% (1.0-2.0%) and 1.5% (1.2-2.1%), respectively. Duplicate measurements of Hbmass on the same day are feasible and show TE similar to triplicate measurements on separate days.
ABSTRACT
The purpose of this study was to investigate changes in post-exercise heart rate recovery (HRR) and heart rate variability (HRV) during an overload-tapering paradigm in marathon runners and examine their relationship with running performance. 9 male runners followed a training program composed of 3 weeks of overload followed by 3 weeks of tapering (-33 ± 7%). Before and after overload and during tapering they performed an exhaustive running test (T(lim)). At the end of this test, HRR variables (e.g. HRR during the first 60 s; HRR(60 s)) and vagal-related HRV indices (e.g. RMSSD(5-10 min)) were examined. T(lim) did not change during the overload training phase (603 ± 105 vs. 614 ± 132 s; P = 0.992), but increased (727 ± 185 s; P = 0.035) during the second week of tapering. Compared with overload, RMSSD(5-10 min) (7.6 ± 3.3 vs. 8.6 ± 2.9 ms; P = 0.045) was reduced after the 2(nd) week of tapering. During tapering, the improvements in T(lim) were negatively correlated with the change in HRR(60 s) (r = -0.84; P = 0.005) but not RMSSD(5-10 min) (r = -0.21; P = 0.59). A slower HRR during marathon tapering may be indicative of improved performance. In contrast, the monitoring of changes in HRV as measured in the present study (i.e. after exercise on a single day), may have little or no additive value.
