The relationship between cardiac damage biomarkers and heart rate variability following 60 min of running.

PURPOSE: Endurance exercise may cause transient alterations in cardiac tissue. The number of studies evaluating the relationship between changes in heart rate variability (HRV) and cardiac biomarkers following an endurance event is limited. We hypothesized that there would be a time-dependent correlation between biomarkers of cardiac damage and the reduction in parasympathetic indices of HRV within 24 h after 60 min of running in middle-aged recreational runners. METHODS: The trained, middle-aged runners who participated in this study ran 60 min at a half-marathon pace on a treadmill. Blood samples (before and 0, 4, and 24 h after the running test) and HRV data (before and 0, 1, 4, and 24 h after the running test) were obtained. RESULTS: After running, cardiac biomarkers (total creatine kinase, cardiac isoform of creatine kinase, creatine kinase-index [CK-Index], cardiac troponin [cTnI]) increased significantly, and HRV measures related to parasympathetic nervous system activity decreased significantly; these measures returned to baseline levels within 24 h. Finally, there were significant correlations (all p < 0.05) between the change (4 h post-running vs. pre-running) in the CK-Index and the changes (post- vs pre-running) in time-domain and nonlinear measures of HRV (r - 0.61 to - 0.67). In addition, significant correlations (all p < 0.05) were found between the area under the cTnI curve and change (1-h post- and pre-running) in time-domain and nonlinear measures of HRV (r - 0.48 to - 0.51). CONCLUSIONS: The correlation between HRV and cardiac biomarkers indicates that HRV analysis may be an alternative approach to determine the magnitude of cardiac stress after endurance exercises.

Effects of a supervised therapeutic exercise program on musculoskeletal health and gait in patients with haemophilia: A pilot study.

INTRODUCTION: Episodes of bleeding in patients with haemophilia (PwH) are associated with haemophilic arthropathy, limitations in physical performance, reduced quality of life (QoL), and gait disorders. AIM: This non-randomized, controlled, interventional, prospective, single-centre pilot study aimed to assess the effects of an 8-week supervised therapeutic exercise program on musculoskeletal health, gait kinematic parameters (GKP), functional capacity, and QoL in adult PwH. METHODS: Nineteen PwH were allocated to an exercise group (n = 10) or a control group (n = 9). The patients in the exercise group followed an 8-week supervised therapeutic exercise program. The Haemophilia Joint Health Score (HJHS), a two-dimensional video-based gait kinematic analysis (2D-GKA), the 6-min walking test (6MWT), and the Haemophilia Quality of Life Questionnaire for Adults (Haem-A-Qol) were used as the outcome measures at baseline, after the exercise program (at the 8th week), and at the 6th-month follow-up. RESULTS: A significant improvement was observed in the exercise group in the HJHS-Total and Haem-A-Qol Total scores and the 6MWT value after the exercise program. Moreover, the 2D-GKA revealed improvement in most of the GKP (knee extension during the midstance and late swing phases, ankle dorsiflexion during the midstance phase, and ankle plantar flexion during the preswing phase). However, the gain obtained by the exercise program was not maintained at the 6th-month follow-up for the HJHS-Total and Hem-A-QoL-Total scores and GKP. CONCLUSION: The 8-week supervised therapeutic exercise program was successful in achieving improvement in joint health, GKP, functional capacity, and QoL in PwH.

A Comparison of the Maximal Fat Oxidation Rates of Three Different Time Periods in The Fatmax Stage.

This study aimed to compare the maximal fat oxidation (MFO) rates obtained from the stage average, last 2 min average, and highest value in the Fatmax stage determined with a 6 min step protocol. A total of 35 overweight, sedentary healthy men (age: 25.4 ± 0.7 years, body mass index: 26.0 ± 0.6 kg/m2) participated in the study. Substrate oxidation was calculated using breath-by-breath gas exchange data for each stage. When the change in the fat oxidation rate for every min throughout the Fatmax stage was evaluated, the average value of the 4th min was significantly lower than that of the 2nd and 3rd min (p < 0.01). In addition, the 5th and 6th min fat oxidation rates were significantly lower than the rates of the 1st, 2nd, 3rd, and 4th min (0.30 ± 0.01 and 0.29 ± 0.01 g/min for the 5th and 6th min, respectively, vs. 0.35 ± 0.02, 0.34 ± 0.02, 0.33 ± 0.02, and 0.31 ± 0.01 g/min for the 1st, 2nd, 3rd, and 4th min, respectively; p < 0.01). Most of the participants had MFO rates in the 1st min of the stage (16/35 participants), and the MFO rates of the remaining participants were observed in the 2nd, 3rd, and 4th min (7/35, 4/35, and 8/35 participants, respectively). None of the participants had MFO rates in the 5th or 6th min. The individual MFO rate (highest fat oxidation rate during Fatmax) was significantly higher than the fat oxidation rate calculated with the last 2 min average values (0.36 ± 0.02 and 0.30 ± 0.01 g/min, respectively; p < 0.05). In conclusion, the calculation of the fat oxidation rate by averaging the last portion of the Fatmax stage data may cause the underestimation of the MFO rate, which probably occurs earlier in the Fatmax stage.