Influence of Different Treadmill Inclinations on V̇o2max and Ventilatory Thresholds During Maximal Ramp Protocols.

ABSTRACT: Silva, SC, Monteiro, WD, Cunha, FA, and Farinatti, P. Influence of different treadmill inclinations on V̇o2max and ventilatory thresholds during maximal ramp protocols. J Strength Cond Res 35(1): 233-239, 2021-Ramp protocols for cardiopulmonary exercise testing (CPET) lack precise recommendations, including optimal treadmill inclination. This study investigated the impact of treadmill grades applied in ramp CPETs on maximal oxygen uptake (V̇o2max), ventilatory thresholds (VT1/VT2), and V̇o2 vs. workload relationship. Twenty-one healthy men (age 33 ± 8 years; height 176.6 ± 5.8 cm; body mass 80.4 ± 8.7 kg; and V̇o2max 44.9 ± 5.7 ml·kg-1·min-1) and 12 women (age 29 ± 7 years; height 163.3 ± 6.7 cm; body mass 56.6 ± 6.3 kg; and V̇o2max 39.4 ± 4.9 ml·kg-1·min-1) underwent ramp CPETs with similar speed increments and different treadmill grades: CPET0%, CPET2%, CPET3.5%, and CPET5.5%. The V̇o2max was similar across protocols (42.8-43.2 ml·kg-1·min-1, p = 0.76), albeit duration of CPETs shortened when treadmill inclination increased (CPET0% 12.7 minutes; CPET2% 9.1 minutes; CPET3.5% 8.0 minutes; and CPET5.5% 6.6 minutes; p < 0.01). The %V̇o2max corresponding to VT1 was slightly lower in CPET0% (63.6%) and higher in CPET5.5% (75.8%) vs. CPET2% (67.8%) and CPET3.5% (69.5%; p < 0.05), whereas VT2 was not affected by treadmill inclination (95.1-95.8% V̇o2max; p > 0.05). V̇o2max and ventilatory thresholds were similar in CPETs performed with different treadmill inclinations and similar initial/final speeds. However, linear regressions between workload and V̇o2 were closer to the identity line in CPETs performed with smaller (CPET0% and CPET2%) than with greater (CPET3.5% and CPET5.5%) inclinations. These data suggest that in healthy young adults, ramp CPETs performed with inclinations of 0-2% degree should be preferred over protocols with greater inclinations.

Effect of bright light therapy on delayed sleep/wake cycle and reaction time of athletes participating in the Rio 2016 Olympic Games.

This study investigated the effect of using an artificial bright light on the entrainment of the sleep/wake cycle as well as the reaction times of athletes before the Rio 2016 Olympic Games. A total of 22 athletes from the Brazilian Olympic Swimming Team were evaluated, with the aim of preparing them to compete at a time when they would normally be about to go to bed for the night. During the 8-day acclimatization period, their sleep/wake cycles were assessed by actigraphy, with all the athletes being treated with artificial light therapy for between 30 and 45 min (starting at day 3). In addition, other recommendations to improve sleep hygiene were made to the athletes. In order to assess reaction times, the Psychomotor Vigilance Test was performed before (day 1) and after (day 8) the bright light therapy. As a result of the intervention, the athletes slept later on the third (p = 0.01), seventh (p = 0.01) and eighth (p = 0.01) days after starting bright light therapy. Regarding reaction times, when tested in the morning the athletes showed improved average (p = 0.01) and minimum reaction time (p = 0.03) when comparing day 8 to day 1. When tested in the evening, they showed improved average (p = 0.04), minimum (p = 0.03) and maximum reaction time (p = 0.02) when comparing day 8 to day 1. Light therapy treatment delayed the sleep/wake cycles and improved reaction times of members of the swimming team. The use of bright light therapy was shown to be effective in modulating the sleep/wake cycles of athletes who had to perform in competitions that took place late at night.

Determination of Best Criteria to Determine Final and Initial Speeds within Ramp Exercise Testing Protocols.

This study compared strategies to define final and initial speeds for designing ramp protocols. V(O(2)max ) was directly assessed in 117 subjects (29 ± 8 yrs) and estimated by three nonexercise models: (1) Veterans Specific Activity Questionnaire (VSAQ); (2) Rating of Perceived Capacity (RPC); (3) Questionnaire of Cardiorespiratory Fitness (CRF). Thirty seven subjects (30 ± 9 yrs) performed three additional tests with initial speeds corresponding to 50% of estimated V(O(2)max ) and 50% and 60% of measured V(O(2)max ). Significant differences (P < 0.001) were found between V(O(2)max ) measured (41.5 ± 6.6 mL·kg(-1)·min(-1)) and estimated by VSAQ (36.6 ± 6.6 mL·kg(-1)·min(-1)) and CRF (45.0 ± 5.3 mL·kg(-1)·min(-1)), but not RPC (41.3 ± 6.2 mL·kg(-1)·min(-1)). The CRF had the highest ICC, the lowest SEE, and better limits of agreement with V(O(2)max ) compared to the other instruments. Initial speeds from 50%-60% V(O(2)max ) estimated by CRF or measured produced similar V(O(2)max ) (40.7 ± 5.9; 40.0 ± 5.6; 40.3 ± 5.5 mL·kg(-1)·min(-1) resp., P = 0.14). The closest relationship to identity line was found in tests beginning at 50% V(O(2)max ) estimated by CRF. In conclusion, CRF was the best option to estimate V(O(2)max ) and therefore to define the final speed for ramp protocols. The measured V(O(2)max ) was independent of initial speeds, but speeds higher than 50% V(O(2)max ) produced poorer submaximal relationships between workload and V(O(2) ).