Performance during consecutive days of laboratory time-trials in young and veteran cyclists

There is a common belief amongst athletes and coaches that older athletes need longer recovery time between training sessions and following competition. This study was undertaken to investigate the influence of age on recovery from high intensity endurance exercise in well-trained cyclists. Nine young and 9 veteran cyclists (mean±SD: young 24±5 years, veteran 45±6 years) performed 3 consecutive days (T1-T3) of laboratory based cycling time trials of 30-min duration (TT30). Mean power output, heart rate (HR), and blood lactate were measured throughout each TT30. Non-specific performance tests of fatigue were undertaken before and after the TT30 on each test day. Non-specific tests included, a maximal voluntary isometric contraction of the quadriceps muscle (MVIF), a countermovement jump (CMJ), a 10-s cycle sprint (10ST), and serum creatine kinase activity (CK). Statistical analysis revealed that there were no significant group differences between young and veteran subjects for initial fitness or training status. Over T1-T3 both groups maintained average power during the TT30 (young and veteran results combined; 3.49±0.38, 3.5±0.36 and 3.52±0.35 W-kg-1, T1T3, respectively). For both groups serum CK activity was significantly elevated at T2 and T3, and mean HR during the TT30 was significantly lower at T3 (~3 b.min^sup -1^). There were no group differences or significant within group interactions across the 3 days for MVIF or 10ST but there was a significantly lower CMJ height by T3 in both young and veteran (~3%). MVIF was significantly lower after TT30 each day but had fully recovered by the following day. These findings suggest that high-intensity endurance performance is maintained in both well-trained young and veteran cyclists following 3 consecutive days of maximal 30min laboratory time trials

Heart rate variability is related to impaired haemorheology in older women with type 2 diabetes

Impaired heart rate variability (HRV) and haemorheology are independently associated with cardiovascular disease and diabetic complications. The aim of the present study was to investigate the relationships between parameters of HRV, and red blood cell (RBC) aggregation and deformability, in older women with type 2 diabetes. Twenty women (age 69±2 yr) with uncomplicated type 2 diabetes and twenty controls (age 69±3 yr) participated in the study. Beat-to-beat cardiac (RR) intervals over 5 min were analysed for HRV parameters in the time and frequency domains. Blood was sampled for RBC deformability, as well as RBC aggregation in two suspending mediums: haematocrit adjusted plasma and 3% dextran 70. RBC aggregation was increased and HRV was impaired for those with type 2 diabetes when compared with control. RBC aggregation was negatively related to low frequency power of HRV, and was positively related to high frequency power of HRV, for subjects with type 2 diabetes. RBC deformability was positively related to HRV only for those with type 2 diabetes. Impaired haemorheology is associated with reduced HRV in older women with type 2 diabetes, suggesting changes in the microcirculation may result in impaired modulation of cardiac cycles

Heart rate variability is related to impaired haemorheology in older women with type 2 diabetes

Impaired heart rate variability (HRV) and haemorheology are independently associated with cardiovascular disease and diabetic complications. The aim of the present study was to investigate the relationships between parameters of HRV, and red blood cell (RBC) aggregation and deformability, in older women with type 2 diabetes. Twenty women (age 69±2 yr) with uncomplicated type 2 diabetes and twenty controls (age 69±3 yr) participated in the study. Beat-to-beat cardiac (RR) intervals over 5 min were analysed for HRV parameters in the time and frequency domains. Blood was sampled for RBC deformability, as well as RBC aggregation in two suspending mediums: haematocrit adjusted plasma and 3% dextran 70. RBC aggregation was increased and HRV was impaired for those with type 2 diabetes when compared with control. RBC aggregation was negatively related to low frequency power of HRV, and was positively related to high frequency power of HRV, for subjects with type 2 diabetes. RBC deformability was positively related to HRV only for those with type 2 diabetes. Impaired haemorheology is associated with reduced HRV in older women with type 2 diabetes, suggesting changes in the microcirculation may result in impaired modulation of cardiac cycles