The Relationship between Running Power and Running Economy in Well-Trained Distance Runners.

A novel running wearable called the Stryd Summit footpod fastens to a runner's shoe and estimates running power. The footpod separates power output into two components, Stryd power and form power. The purpose of this study was to measure the correlations between running economy and power and form power at lactate threshold pace. Seventeen well-trained distance runners, 9 male and 8 female, completed a running protocol. Participants ran two four-minute trials: one with a self-selected cadence, and one with a target cadence lowered by 10%. The mean running economy expressed in terms of oxygen cost at self-selected cadence was 201.6 ± 12.8 mL·kg-1·km-1, and at lowered cadence was 204.5 ± 11.5 mL·kg-1·km-1. Ventilation rate and rating of perceived exertion (RPE) were not significantly different between cadence conditions with one-tailed paired t-test analysis (ventilation, p = 0.77, RPE, p = 0.07). Respiratory exchange ratio and caloric unit cost were significantly greater with lower cadence condition (respiratory exchange ratio, p = 0.03, caloric unit cost, p = 0.03). Mean power at self-selected cadence was 4.4 ± 0.5 W·kg-1, and at lowered cadence was 4.4 ± 0.5 W·kg-1. Mean form power at self-selected cadence was 1.1 ± 0.1 W·kg-1, and at lowered cadence was 1.1 ± 0.1 W·kg-1. There were positive, linear correlations between running economy and power (self-selected cadence and lower cadence, r = 0.6; the 90% confidence interval was 0.2 to 0.8); running economy and form power (self-selected cadence and lower cadence r = 0.5; the 90% confidence interval was 0.1 to 0.8). The findings suggest running economy is positively correlated with Stryd's power and form power measures yet the footpod may not be sufficiently accurate to estimate differences in the running economy of competitive runners.

Run Economy on a Normal and Lower Body Positive Pressure Treadmill.

Lower body positive pressure (LBPP) treadmill running is used more frequently in clinical and athletic settings. Accurate caloric expenditure is required for proper exercise prescription, especially for obese patients performing LBPP exercise. It is unclear if running on LBPP changes running economy (RE) in proportion to the changes in body weight. The purpose of the study was to measure the oxygen consumption (VO2) and running economy (RE) of treadmill running at normal body weight and on LBPP. Twenty-three active, non-obese participants (25.8±7.2 years; BMI = 25.52±3.29 kg·m-2) completed two bouts of running exercise in a counterbalanced manner: (a) on a normal treadmill (NT) and (b) on a LBPP treadmill at 60% (40% of body weight supported) for 4 min at 2.24 (5 mph), 2.68 (6 mph), and 3.13 m·s-1 (7 mph). Repeated measures ANOVA showed a statistically significant interaction in RE among trials, F(2, 44) = 6.510, p <.0005, partial η2 = 0.228. An examination of pairwise comparisons indicated that RE was significantly greater for LBPP across the three speeds (p < 0.005). As expected, LBPP treadmill running resulted in significantly lower oxygen consumption at all three running speeds. We conclude that RE (ml O2·kg-1·km-1) of LBPP running is significantly poorer than normal treadmill running, and the ~30% change in absolute energy cost is not as great as predicted by the change in body weight (40%).

Four Weeks of Off-Season Training Improves Peak Oxygen Consumption in Female Field Hockey Players.

The purpose of the study was to examine the changes in peak oxygen consumption ( V ˙O2peak) and running economy (RE) following four-weeks of high intensity training and concurrent strength and conditioning during the off-season in collegiate female field hockey players. Fourteen female student-athletes (age 19.29 ± 0.91 years) were divided into two training groups, matched from baseline V ˙O2peak: High Intensity Training (HITrun; n = 8) and High Intensity Interval Training (HIIT; n = 6). Participants completed 12 training sessions. HITrun consisted of 30 min of high-intensity running, while HIIT consisted of a series of whole-body high intensity Tabata-style intervals (75⁻85% of age predicted maximum heart rate) for a total of four minutes. In addition to the interval training, the off-season training included six resistance training sessions, three team practices, and concluded with a team scrimmage. V ˙O2peak was measured pre- and post-training to determine the effectiveness of the training program. A two-way mixed (group × time) ANOVA showed a main effect of time with a statistically significant difference in V ˙O2peak from pre- to post-testing, F(1, 12) = 12.657, p = 0.004, partial η² = 0.041. Average (±SD) V ˙O2peak increased from 44.64 ± 3.74 to 47.35 ± 3.16 mL·kg-1·min-1 for HIIT group and increased from 45.39 ± 2.80 to 48.22 ± 2.42 mL·kg-1·min-1 for HITrun group. Given the similar improvement in aerobic power, coaches and training staff may find the time saving element of HIIT-type conditioning programs attractive.

Cognitive influence of a 5-h ENERGY® shot: Are effects perceived or real?

With the gain in popularity and use of 'functional energy drinks' (FEDs), manufacturers of these beverages have been making greater claims as to their benefits on a number of performance factors including mental alertness, energy, and physical performance. Few experimental studies have been conducted on FEDs, and no study to date has examined their effects over time. This study looked at the effects of consumption of a 5-h ENERGY® shot (5-HES) on various cognitive functions across five hours on 24 college-aged students using a double-blind, cross-over, placebo-based design. Participants completed a series of five computer-based tests before ingesting the beverage (either 5-HES or placebo) and then completed the tests for each of the next five hours (morning to midday). One week later, they repeated the process with the other beverage. While 90% of participants subjectively thought that the 5-HES was effective at one-hour post-ingestion, no evidence was found to support an enhanced effect on recognition, reaction time, short-term and working memory, or attention capacity. In conclusion, the 5-h Energy Shot® did not significantly improve short- or long-term cognitive function for selected computer-based tasks despite a high level of perception that it was working effectively compared to a placebo with college-aged participants.