What is running economy? A clinician's guide to key concepts, applications and myths

Effects of Training on Running Cost and Aerobic Capacity in Individuals with Obesity

This study investigated running cost (CRun), peak oxygen consumption (V̇ O2peak), and ventilatory threshold (VT1) responses to exercise programs for individuals with obesity. Ninety-four individuals (38.2±7.7 years; 33.4±2.9 kg/m²) were assigned into strength (n=24), endurance (n=26), combined (n=22), and physical activity (control, n=22) groups for 22 weeks, plus diet recommendation. The V̇ O2peak, VT1, and CRun were assessed through a maximal incremental step test. The change of V̇ O2peak in combined (9.9%) differed from the other groups, with lower values in women than men (0.7% vs. 6.2%). The VT1 change in combined (16.4%) differed from the strength (4.9%) and physical activity (1.2%) groups, with the change in endurance (12.7%) also being higher than the physical activity group. Only men in the combined group increased absolute V̇ O2peak, while both sexes increased VT1 in the endurance and combined groups. No effects for groups and sex were significant for CRun in moderate (VT1) running zones, despite CRun changes in VT1 zones correlated with the alterations of V̇ O2peak and VT1 (r²=0.29-0.59). Therefore, moderate aerobic exercise stimulus is suitable for VT1 improvement in individuals with obesity, with the increase in CRun associated to the chances of increasing V̇ O2peak in men and when combining strength with aerobic exercises.

Influence of Chronic Nitrate-Rich Beetroot Juice Supplementation on the Endurance Performance of Active Winter Triathletes: A Randomized Controlled Trial

OBJECTIVE

The impact of high-nitrate beetroot juice (BRJ) supplementation has seen a recent explosion of interest in sports science. This study examined the potential influence of 7-day BRJ supplementation on the endurance performance of winter triathletes.

METHODS

Eighty young active winter triathletes (44 males, age = 21.50 ± 1.15 yrs; 36 females, age = 20.66 ± 1.45 yrs) participated in this study and were provided with either BRJ (6.5 mmol NO₃^-/70 mL) or a placebo (PL, 0.065 mmol NO₃^-/70 mL) for 7 days (a dose of ×3 per day) in a randomized, double-blind design. The athletes then completed a submaximal treadmill run, intraday cycling exhaustion testing, and a 10-km cross country (XC) skiing competition on the second day.

RESULTS

There was a significant decrease in the oxygen uptake, respiratory exchange ratio, and blood lactic acid level (p < 0.05) between the BRJ and PL treatment groups during V₃ speed running (males: 13.3 km·h^-1, females: 11.6 km·h^-1). BRJ treatment also remarkably increased the time to exhaustion (TTE) during cycling exhaustion testing (males: p = 0.02, females: p = 0.04). No significant differences were observed in medium- or low-speed submaximal treadmill runs and 10-km XC skiing performance.

CONCLUSIONS

One week of daily nitrate-rich BRJ supplementation improved running economy at high speed during the submaximal treadmill running test and extended the TTE of athletes during cycling exhaustion testing. However, BRJ supplementation did not improve the performance in 10-km on-snow time trials in XC skiing. Regarding nutritional strategies to improve endurance performance in exercise training and competition, these results should be carefully considered owing to the different motor skill levels and competitive abilities of participants.

Aerobic interval training improves maximal oxygen uptake and reduces body fat in grapplers

BACKGROUND

Despite regularly engaging in high-intensity grappling, Brazilian jiu-jitsu (BJJ) athletes have a moderate maximal oxygen uptake (V̇O2max). The aim of this study was to evaluate the efficacy and feasibility of high-intensity aerobic interval training as an accessory to BJJ training for improvements in V̇O2max.

METHODS

Twelve active male BJJ practitioners (age: 30.3±4.0 [SD] years; height: 183.0±5.3 cm; body mass: 82.7±8.3 kg; body fat: 11.9±3.8%) with 5.6±5.8 years of experience and a training volume of 9.9±4.6 hours·week-1 were randomly allocated to either a training group (TG) or control group (CG). The TG incorporated two high-intensity aerobic interval training sessions·week-1 comprising four 4-minute intervals at 85-95% of maximal heart rate (HRmax) separated by 3-minute active breaks at 70% of HRmax.

RESULTS

After six weeks, the TG increased their V̇O2max by 8±3% (95% CI=3.84, 12.73; P=0.04; ES=0.64), from 52.7 to 56.8 mL·kg-1·min-1. This was accompanied by a 1±1% reduction in absolute body fat (95% CI=-0.13, -2.2; P=0.04; ES=0.64). No changes in V̇O2max (P=0.12) or body composition (P=0.34) were detected in the CG.

CONCLUSIONS

These findings reveal compelling short-term effects of low-volume high-intensity aerobic interval training on V̇O2max and body composition in active BJJ athletes. There may be a ceiling effect in terms of developing V̇O2max in supine, intermittent grappling sports, making alternative approaches to aerobic conditioning particularly relevant for this athlete population.

Running Performance, VO2max, and Running Economy: The Widespread Issue of Endogenous Selection Bias

Studies in sport and exercise medicine routinely use samples of highly trained individuals in order to understand what characterizes elite endurance performance, such as running economy and maximal oxygen uptake VO_2max. However, it is not well understood in the literature that using such samples most certainly leads to biased findings and accordingly potentially erroneous conclusions because of endogenous selection bias. In this paper, I review the current literature on running economy and VO_2max, and discuss the literature in light of endogenous selection bias. I demonstrate that the results in a large part of the literature may be misleading, and provide some practical suggestions as to how future studies may alleviate endogenous selection bias.

Anthropometric and Physiological Characteristics of Brazilian Jiu-Jitsu Athletes

Øvretveit, K. Anthropometric and physiological characteristics of Brazilian jiu-jitsu athletes. J Strength Cond Res 32(4): 997-1004, 2018-The aim of this study was to describe anthropometric and physiological characteristics of Brazilian jiu-jitsu (BJJ) athletes. For this purpose, 42 male athletes were recruited from one of the largest BJJ academies in central Norway. The subjects were 32 ± 6 (SD) years old, 181.9 ± 7.2 cm tall, had a body mass (mb) of 85.7 ± 10.6 kg, and 5.5 ± 3.7 years of BJJ training experience. The subjects underwent segmental multifrequency bioelectrical impedance analysis of body composition (BIA), direct measurements of pulmonary function and maximal oxygen uptake (V[Combining Dot Above]O2max), assessments of 1-repetition maximum (1RM) in the parallel squat and paused bench press, and one set of pronated-grip pull-ups to muscular failure. The average body fat percentage (BF) was 12.9 ± 5.3%. The subjects achieved a V[Combining Dot Above]O2max of 50.6 ± 4.6 mL·kg·min. Absolute squat 1RM (113.2 ± 20.4 kg) was significantly higher than bench press 1RM (87.6 ± 16.5 kg) (p < 0.001). The mean number of pull-ups achieved was 9 ± 4. These characteristics were generally independent of rank, training experience, weekly training volume, competition volume, and style preference. Additional strength training was associated with improved bench press performance (p < 0.05). Beyond that, additional strength and/or conditioning training had no apparent relationship with any variable (p > 0.05). This study provides novel insight into the fitness levels of BJJ athletes. These findings indicate the degree of exercise response to BJJ training and are applicable in athlete assessment and exercise prescription in this population.