Maximal oxygen uptake (V̇O2max), fractional utilization of V̇O2max during running, and running economy (RE) are crucial factors for running success for all endurance athletes. Although evidence is limited, investigations of these key factors indicate that East Africans’ superiority in distance running is largely due to a unique combination of these factors. East African runners appear to have a very high level of RE most likely associated, at least partly, with anthropometric characteristics rather than with any specific metabolic property of the working muscle. That is, evidence suggest that anthropometrics and body composition might have important parameters as determinants of superior performance of East African distance runners. Regrettably, this role is often overlooked and mentioned as a descriptive parameter rather than an explanatory parameter in many research studies. This brief review article provides an overview of the evidence to support the critical role anthropometrics and body composition has on the distance running success of East African athletes. The structural form and shape of these athletes also has a downside, because having very low BMI or body fat increases the risk for relative energy deficiency in sport (RED-S) conditions in both male and female runners, which can have serious health consequences.
Martin Mooses and Anthony C. Hackney
Renato Evangelista, Rafael Pereira, Anthony C. Hackney, and Marco Machado
To compare differences between two different rest interval lengths between sets on the volume completed, muscle damage and muscle soreness during a resistance exercise bout.
Twenty-eight healthy sedentary men (18 ± 1 y old) volunteered to participate in this study and were divided into the 1 min (1RI; n = 14) or 3 min (3RI; n = 14) rest interval length between sets. They were submitted to maximal voluntary isometric contraction strength (MVC) and then performed a resistance exercise protocol constituted for three sets of biceps curl at 40% of MVC with 1 min (1RI group) or 3 min (3RI group) interval length between sets. Each bout was performed to voluntary fatigue and the workout volume completed was calculated. Subjects provided blood samples before each bout, and at 24, and 48 h following exercise to evaluate serum CK activity. Muscle soreness was analyzed through visual analog scale, which was presented to subjects before frst bout, immediately after exercise protocol and at 24, and 48 h following exercise.
The results demonstrated that the subjects with longer rest intervals provide greater workout volume as expected, but there were no differences in serum CK activity and muscle soreness between groups.
Training with highvolume, low-intensity resistance training, exercising with short rest intervals does not appear to present any additional challenge to recovery in untrained subjects.
Travis Anderson, Amy R. Lane, and Anthony C. Hackney
The cortisol awakening response (CAR) is commonly used as a marker of psychological stress; however, it is unknown whether CAR is affected by regular physical-exercise-induced stress. Purpose: To assess the relationship between training load and CAR. Methods: Recreational endurance athletes were recruited from local running clubs. Subjects (n = 15) completed training logs for 2 wk, with various training loads, including psychometric analysis (Recovery-Stress Questionnaire for Athletes). Subjects provided saliva samples each day immediately after waking and 30 min postwaking. Samples were analyzed for cortisol concentration via enzyme-linked immunosorbent assay and subsequently were analyzed for CAR and CAR%. Daily training load was calculated and analyzed as training impulse. Simple linear regression was used to assess the relationship between CAR and training impulse. Results: CAR (r 2 = .352, P = .025) and CAR% (r 2 = .373, P = .012) both showed a significant negative relationship with training load. Conclusions: These results suggest that CAR is affected by regular exercise training loads in recreational athletes. It is recommended that future CAR research control for fitness level and exercise training load in physically active populations.
Anthony C. Hackney, Mary Ann McCracken-Compton, and Barbara Ainsworth
This study examined substrate metabolism responses of eumenorrheic women to different intensities of submaximai exercise at the midfollicular (MF) and the midluteal (ML) phases of the menstrual cycle. Nine women performed a 30-min treadmill run in which the exercise intensity was made more difficult every 10 min (35%, 60%, and 75%). Carbohydrate (CHO) utilization and oxidation rates for the 35% and 60% intensities during the ML session were significantly lower than during the comparable intensities in the MF. Conversely, lipid utilization and oxidation were significantly greater during the 35% and 60% ML session than in the MF session. At 75%, however, the ML and MF CHO-lipid utilization and oxidation rates were not significantly different from one another. Thus, the phase of the menstrual cycle in eumenorrheic women does influence metabolic substrate usage during low- to moderate-intensity submaximai exercise, probably due to changes in the endogenous levels of the female sex hormones.
Mitch D. VanBruggen, Anthony C. Hackney, Robert G. McMurray, and Kristin S. Ondrak
The effect of exercise intensity on the tracking of serum and salivary cortisol responses was examined in 12 endurance-trained males (maximal oxygen uptake [VO2max] = 58.2 ± 6.4 mL/kg/min).
Subjects rested for 30 min (control) and exercised on a cycle ergometer for 30 min at 40% (low), 60% (moderate), and 80% (high intensity) of VO2max on separate days. Serum and saliva samples were collected pretrial, immediately posttrial, and 30 min into the recovery period from each trial.
Cortisol responses increased significantly for both serum (40.4%; P = .001) and saliva (170.6%; P = .007) only in response to high-intensity exercise. Peak saliva cortisol occurred at 30 min of recovery, whereas peak serum was at the immediate posttrial sampling time point. The association between serum and saliva cortisol across all trials was examined using concordance correlation (R c) analysis, which accounts for repeated measures. The overall correlation between serum and saliva cortisol levels in all matched samples was significant (R c = 0.728; P = .001). The scatter plot revealed that salivary cortisol responses tracked closely to those of serum at lower concentrations, but not as well at higher concentrations.
Findings suggest salivary measurements of cortisol closely mirror those in the serum and that peak salivary concentrations do not occur until at least 30 min into the recovery from intense exercise.
Ali Daraei, Sajad Ahmadizad, Hiwa Rahmani, Anthony C. Hackney, Kelly E. Johnson, Ismail Laher, Ayoub Saeidi, and Hassane Zouhal
The effects of acute consumption of L-Arginine (L-Arg) in healthy young individuals are not clearly defined, and no studies on the effects of L-Arg in individuals with abnormal body mass index undertaking strenuous exercise exist. Thus, we examined whether supplementation with L-Arg diminishes cardiopulmonary exercise testing responses, such as ventilation (VE), VE/VCO2, oxygen uptake (VO2), and heart rate, in response to an acute session of high-intensity interval exercise (HIIE) in overweight men. A double-blind, randomized crossover design was used to study 30 overweight men (age, 26.5 ± 2.2 years; body weight, 88.2 ± 5.3 kilogram; body mass index, 28.0 ± 1.4 kg/m2). Participants first completed a ramped-treadmill exercise protocol to determine VO2max velocity (vVO2max), after which they participated in two sessions of HIIE. Participants were randomly assigned to receive either 6 g of L-Arg or placebo supplements. The HIIE treadmill running protocol consisted of 12 trials, including exercise at 100% of vVO2max for 1 min interspersed with recovery intervals of 40% of vVO2max for 2 min. Measurements of VO2 (ml·kg−1·min−1), VE (L/min), heart rate (beat per min), and VE/VCO2 were obtained. Supplementation with L-Arg significantly decreased all cardiorespiratory responses during HIIE (placebo+HIIE vs. L-Arg+HIIE for each measurement: VE [80.9 ± 4.3 L/min vs. 74.6 ± 3.5 L/min, p < .05, ES = 1.61], VE/VCO2 [26.4 ± 1.3 vs. 24.4 ± 1.0, p < .05, ES = 1.8], VO2 [26.4 ± 0.8 ml·kg−1·min−1 vs. 24.4 ± 0.9 ml·kg−1·min−1, p < .05, ES = 2.2], and heart rate [159.7 ± 6.3 beats/min vs. 155.0 ± 3.7 beats/min, p < .05, d = 0.89]). The authors conclude consuming L-Arg before HIIE can alleviate the excessive physiological strain resulting from HIIE and help to increase exercise tolerance in participants with a higher body mass index who may need to exercise on a regular basis for extended periods to improve their health.
Johanna K. Ihalainen, Oona Kettunen, Kerry McGawley, Guro Strøm Solli, Anthony C. Hackney, Antti A. Mero, and Heikki Kyröläinen
Purpose: To determine body composition, energy availability, training load, and menstrual status in young elite endurance running athletes (ATH) over 1 year, and in a secondary analysis, to investigate how these factors differ between nonrunning controls (CON), and amenorrheic (AME) and eumenorrheic (EUM) ATH. Correlations to injury, illness, and performance were also examined. Methods: Altogether 13 ATH and 8 CON completed the Low Energy Availability in Females Questionnaire. Anthropometric, energy intake, and peak oxygen uptake assessments were made at 4 time points throughout the year: at baseline post competition season, post general preparation, post specific preparation, and post competition season the following year. Logs of physical activity, menstrual cycle, illness, and injury were kept by all participants. Performance was defined using the highest International Association of Athletics Federations points prior to and after the study. Results: ATH had significantly lower body mass (P < .008), fat percentage (P < .001), and body mass index (P < .027) compared with CON, while energy availability did not differ between ATH and CON. The Low Energy Availability in Females Questionnaire score was higher in ATH than in CON (P < .028), and 8 ATH (vs zero CON) were AME. The AME had significantly more injury days (P < .041) and ran less (P < .046) than EUM, while total annual running distance was positively related to changes in performance in ATH (r < .62, P < .043, n < 11). Conclusions: More than half of this group of runners was AME, and they were injured more and ran less than their EUM counterparts. Furthermore, only the EUM runners increased their performance over the course of the year.