Physiological responses to treadmill exercise in size- and fitness-matched male and female firefighter applicants.

Physiological responses during a standardised treadmill test for structural firefighting employment were compared in 41 pairs of size-matched, male and female applicants. Applicants wore personal exercise clothing, running shoes, and fire protective ensemble with self-contained breathing apparatus (added mass 21.2 ± 1.0 kg). Applicants walked at 1.56 m·s-1, completing a 5-min warm-up, 8-min at 10% grade, and then, progressive 1-min stages to exhaustion. The cut-score required completion of 13-min of exercise. Up to the cut-score, no differences in heart rate, oxygen uptake or minute ventilation were detected between sexes. At time 12:30-13:00 min, V̇O2 was 45.7 ± 0.6 vs. 44.2 ± 0.5 mL·kg-1·min-1 (body mass) for males and females, respectively. Despite similar physiological responses at minute 13, females worked at higher fractions of peak than males (p < 0.05). A second analysis compared a subset of 27 fitness-matched (V̇O2peak) male-female pairs. Fitness-matching further reduced or eliminated most observed differences in physiological responses, except small differences in breathing pattern. Practitioner Summary: Physiological responses during a standardised treadmill test for firefighter applicants were investigated in male and female applicants matched on size and fitness. Absolute responses to exercise were the same for both sexes when size-matched, but relative intensity was higher for females. Fitness-matching reduced or eliminated most previously observed differences. Abbreviations: NFPA: National Fire Protection Association; V̇O2: rate of oxygen consumption; V̇O2peak: rate of oxygen consumption at peak exercise; PAR-Q+: Physical Activity Readiness Questionnaire Plus; SCBA: self-contained breathing apparatus; ANOVA: analysis of variance; V̇E: minute ventilation; V̇Epeak: minute ventilation at peak exercise; V̇E/V̇O2: ventilatory equivalent for oxygen.

The Validity and Reliability of a Treadmill Test for Structural Firefighter Applicants.

OBJECTIVE: This 2-part study evaluated validity and reliability of a treadmill test for structural firefighters. METHODS: Wearing fire protective ensemble, 260 participants walked at 1.56 m·s-1, completing a 5-min warm-up, an 8-min stage at a 5.71° incline, then graded stages to exhaustion. In Part 2, 21 participants completed the test on 3 separate days under standardized conditions. RESULTS: Average (±SD) oxygen uptake () during minutes 1-13 was similar to reported values for simulated fire-rescue work. During the 13th min, was consistent with recommendations for firefighters. in Part 2, exercise duration increased between trials 1 and 2 before stabilizing but was consistent. CONCLUSIONS: Congruence with reported during simulated firefighting and recommendations for confirmed validity. Acceptable test-retest reliability was demonstrated. We conclude that the test is valid and reliable for evaluating cardiorespiratory endurance for firefighting.

Ventilatory responses in males and females during graded exercise with and without thoracic load carriage.

PURPOSE AND METHODS: To compare the effects of thoracic load carriage on the ventilatory and perceptual responses to graded exercise, 14 pairs of height-matched, physically active males and females completed randomly ordered modified Balke treadmill exercise tests with and without a correctly sized and fitted 20.4 kg backpack and work clothing. Subjects walked at 1.56 m.s- 1 while grade was increased by 2% every 2 min until exhaustion. Ventilatory responses were measured with open circuit spirometry and perceptual responses were evaluated using the modified Borg scale. Inspiratory capacity maneuvers were performed to calculate operating lung volumes. RESULTS: Despite height matching, males had significantly greater lung volumes and peak oxygen uptake ([Formula: see text]O2peak). Peak [Formula: see text]O2 and ventilation ([Formula: see text]E) were lower (p < 0.05) for all subjects under load. Throughout exercise, the ventilatory equivalents for [Formula: see text]O2 and carbon dioxide production were significantly higher in females, independent of condition. At similar relative submaximal intensities (%[Formula: see text]O2peak), there was no difference in [Formula: see text]E between conditions in either group, however, all subjects adopted a rapid and shallow breathing pattern under load with decreased tidal volume secondary to lower end-inspiratory lung volume. The relative changes in breathing pattern and operating lung volume between unloaded and loaded conditions were similar between males and females. Females reported significantly higher dyspnea ratings for a given [Formula: see text]E compared to males; however, the relationship between dyspnea and [Formula: see text]E was unaffected by load carriage. CONCLUSION: The relative response patterns for ventilatory and perceptual responses to graded exercise with thoracic loading were similar in males and females.

Influence of work clothing on physiological responses and performance during treadmill exercise and the Wildland Firefighter Pack Test.

This study investigated physiological responses and performance during three separate exercise challenges (Parts I, II, and III) with wildland firefighting work clothing ensemble (boots and coveralls) and a 20.4 kg backpack in four conditions: U-EX (no pack, exercise clothing); L-EX (pack, exercise clothing); U-W (no pack, work clothing); and, L-W (pack and work clothing). Part I consisted of randomly-ordered graded exercise tests, on separate days, in U-EX, L-EX and L-W conditions. Part II consisted of randomly-ordered bouts of sub-maximal treadmill exercise in the four conditions. In Part III, subjects completed, in random-order on separate days, 4.83 km Pack Tests in L-EX or L-W conditions. In Part I, peak oxygen uptake was reduced (p < .05) in L-W. In Part II, mass-specific oxygen uptake was significantly higher in both work clothing conditions. In Part III, Pack Test time was slower (p < .05) in L-W. These results demonstrate the negative impact of work clothing and load carriage on physiological responses to exercise and performance.

The impact of thoracic load carriage up to 45 kg on the cardiopulmonary response to exercise.

PURPOSE: The purposes of this experiment were to, first, document the effect of 45-kg thoracic loading on peak exercise responses and, second, the effects of systematic increases in thoracic load on physiological responses to submaximal treadmill walking at a standardized speed and grade. METHODS: On separate days, 19 males (age 27 ± 5 years, height 180.0 ± 7.4 cm, mass 86.9 ± 15.1 kg) completed randomly ordered graded exercise tests to exhaustion in loaded (45 kg) and unloaded conditions. On a third day, each subject completed four randomly ordered, 10-min bouts of treadmill walking at 1.34 m s(-1) and 4 % grade in the following conditions: unloaded, and with backpacks weighted to 15, 30, and 45 kg. RESULTS: With 45-kg thoracic loading, absolute oxygen consumption ([Formula: see text]), minute ventilation, power output, and test duration were significantly decreased at peak exercise. End-inspiratory lung volume and tidal volume were significantly reduced with no changes in end-expiratory lung volume, breathing frequency, and the respiratory exchange ratio. Peak end-tidal carbon dioxide and the ratio of alveolar ventilation to carbon dioxide production were similar between conditions. The reductions in peak physiological responses were greater than expected based on previous research with lighter loads. During submaximal treadmill exercise, [Formula: see text] increased (P < 0.05) by 11.0 (unloaded to 15 kg), 14.5 (15-30 kg), and 18.0 % (30-45 kg) showing that the increase in exercise [Formula: see text] was not proportional to load mass. CONCLUSION: These results provide further insight into the specificity of physiological responses to different types of load carriage.