Jocelito B. Martins

Responses of obese and non-obese boys cycling in the heat.

This study compared rectal temperature (Tre), heat sensation and sweating between obese and non-obese boys during cycling in the heat. Participants (aged 12-15 years) were 17 obese and 16 non-obese (BMI=29.4±4.3 and 16.8±1.7 kg · m⁻², respectively) boys. They cycled for 30-min (50-55% VO(2peak)) in a climatic chamber (35°C, 45% RH) and Tre, heat sensation and sweat volume were monitored. From the start to the end of cycling, Tre was similar between the obese (37.4±0.3-37.8±0.3°C) and non-obese (37.3±0.2-37.9±0.2°C) groups. Heat sensation was higher in the obese group from the start (3.6±2.7 vs. 1.3±1.4 cm; P=0.008) to the end (7.6±2 vs. 5.2±2.2 cm; P=0.003) of cycling. Sweat volume corrected by body surface area was similar between the obese (200±123 mL · m⁻²) and non-obese (212±80 mL · m⁻²) groups. Initial and final HR were similar in both groups, and RPE was higher in the obese group at 25th (P=0.040) and 30th (P=0.019) min. In conclusion, the obese pubescent participants presented similar Tre and sweating volume, but higher heat sensation while cycling in the heat.

Serum S100B level increases after running but not cycling exercise

The objective of this study was to investigate the effect of running versus cycling exercises upon serum S100B levels and typical markers of skeletal muscle damage such as creatine kinase (CK), aspartate aminotransferase (AST) and myoglobin (Mb). Although recent work demonstrates that S100B is highly expressed and exerts functional properties in skeletal muscle, there is no previous study that tries to establish a relationship between muscle damage and serum S100B levels after exercise. We conducted a cross-sectional study on 13 male triathletes. They completed 2 submaximal exercise protocols at anaerobic threshold intensity. Running was performed on a treadmill with no inclination (RUN) and cycling (CYC) using a cycle-simulator. Three blood samples were taken before (PRE), immediately after (POST) and 1 h after exercise for CK, AST, Mb and S100B assessments. We found a significant increase in serum S100B levels and muscle damage markers in RUN POST compared with RUN PRE. Comparing groups, POST S100B, CK, AST and Mb serum levels were higher in RUN than CYC. Only in RUN, the area under the curve (AUC) of serum S100B is positively correlated with AUC of CK and Mb. Therefore, immediately after an intense exercise such as running, but not cycling, serum levels of S100B protein increase in parallel with levels of CK, AST and Mb. Additionally, the positive correlation between S100B and CK and Mb points to S100B as an acute biomarker of muscle damage after running exercise.

Six-minute walk distance and work relationship with incremental treadmill cardiopulmonary exercise test in COPD

Introduction:  Cardiopulmonary exercise testing (CPET) is increasingly used to evaluate the overall impact of the illness on patients with chronic obstructive pulmonary disease (COPD). While laboratory tests of exercise performance are costly, the 6‐min walk test (6‐MWT) can be more easily performed. Although the main outcome commonly used in this field test is the distance walked in 6 min (6‐MWD), this measure does not account for differences in body weight. Previous studies showed a good correlation between the work performed during the 6‐MWT with incremental cycling CPET, an exercise modality more associated with quadriceps fatigability and with lower peak oxygen consumption than incremental walking tests.