RESUMO
BACKGROUND: Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown. HYPOTHESIS: VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA. STUDY DESIGN: Interventional study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc. RESULTS: No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59). CONCLUSION: VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants' similar aerobic training status and high aerobic fitness levels. CLINICAL RELEVANCE: HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.
RESUMO
Clinical Scenario: Chronic exertional compartment syndrome (CECS) is a condition related with ischemia of the body's tissue due to increases in intracompartmental pressures, which involves, among other symptoms, pain with exertion. CECS is often overlooked or misdiagnosed due to an ambiguous presentation. Diagnostic accuracy of CECS and subsequent management can be improved when contributing factors are known. Research is lacking on the type of patient most likely to experience CECS, highlighting the need for identification of common demographic characteristics among affected individuals. Clinical Question: What are the common demographic characteristics among patients exhibiting CECS of the lower leg? Summary of Key Findings: Four studies were identified (1 prospective consecutive study, 2 retrospective reviews, and 1 retrospective cohort study) that examined common characteristics among patients with CECS. Conflicting evidence exists on whether CECS is more commonly seen in men or in women. CECS has often been reported in young, active individuals but may present in older populations as well. Soccer, field hockey, lacrosse, competitive running, and speed skating have been associated with an increased likelihood of CECS development. Clinical Bottom Line: Current evidence has identified commonalities in sex, age, and sport participation as characteristics often present among individuals experiencing lower leg CECS. Other factors, such as overuse, trauma, diabetes, and gait mechanics, have also been identified in association with CECS. Further data through future prospective studies will help confirm the type of patient mostly likely to experience CECS. Strength of Recommendation: Grade B evidence exists that certain sex, age, and sport participation demographic characteristics are common among patients with CECS of the lower leg.