Initial Weekly HRV Response is Related to the Prospective Change in VO2max in Female Soccer Players.

The aim of this study was to determine whether the early response in weekly measures of HRV, when derived from a smartphone application, were related to the eventual change in VO2max following an off-season training program in female soccer athletes. 9 female collegiate soccer players participated in an 11-week off-season conditioning program. In the week immediately before and after the training program, each participant performed a test on a treadmill to determine maximal oxygen consumption (VO2max). Daily measures of the log-transformed root mean square of successive R-R intervals (lnRMSSD) were performed by the participants throughout week 1 and week 3 of the conditioning program. The mean and coefficient of variation (CV) lnRMSSD values of week 1 showed small (r=- 0.13, p=0.74) and moderate (r=0.57, p=0.11), respectively, non-significant correlations to the change in VO2max at the end of the conditioning program (∆VO2max). Significant and near-perfect correlation was found between the change in the weekly mean lnRMSSD values from weeks 1 and 3 (∆lnRMSSDM) and ∆VO2max (r=0.90, p=0.002). The current results have identified that the initial change in weekly mean lnRMSSD from weeks 1 to 3 of a conditioning protocol was strongly associated with the eventual adaptation of VO2max.

Race influences the relationship between aerobic power and heart rate recovery.

AIM: This investigation examined the association between aerobic fitness, race, and heart rate recovery. METHODS: Forty white and 40 black subjects participated in the study and were group matched based on age and maximal oxygen consumption (VO(2max)) which was determined via a maximal graded exercise test on a treadmill. Heart rate recovery was evaluated at 1-minute (HRR1) and at 2-minutes (HRR2) during an active cool-down period. The subjects were divided by race and whether they were above (A) or below (B) the referenced 50th percentile for VO(2max) for men age 20 - 29 years. RESULTS: When evaluating each race separately, the white men who were in the A group had significantly faster HRR1 (18.2 ± 5.9 beats.min-1 in A versus 16.7 ± 6.0 beats.min-1 in B) and HRR2 (40.9 ± 10.3 beats.min-1 in A versus 32.1 ± 8.5 beats.min-1 in B) compared to the white men in the B group. However, there was no significant difference in either HRR1 (18.2 ± 5.9 beats.min-1 in A versus 16.7 ± 6 beats.min-1 in B) or HRR2 (43.1 ± 10.3 beats.min-1 in A versus 44.4.6 ± 8.2 beats.min-1 in B) between the A and B groups in the black men. The only significant correlation existed between VO(2max) and HRR2 in the white subjects (r=0.33, P<0.05). CONCLUSION: The results of this study suggest that HRR is associated with aerobic fitness in white men but not in black men.

The EMG of conventional abdominal exercise and exercise with a semi-upright commercial device: comparative effects and technique considerations.

AIM: The purpose of this study was to measure and compare the muscle activity of the rectus abdominis (RA) and external obliques (EO) with conventional exercises and while using an upright commercial abdominal training device (the CoreMaster). It was hypothesized that the upright device would elicit higher electromyography (EMG) values compared to conventional abdominal exercises. METHODS: Fifteen subjects (8 males, 7 females) participated in this study. Each subject performed 10 repetitions for 5 exercises: truck lift (TL); trunk rotation to opposite knee (TROK); trunk lift on the CoreMaster (TLCM); trunk rotation on the CoreMaster (TRCM); and trunk rotation with a leg lift on the CoreMaster (TRLLCM). Muscle activity was measured for the RA and EO using surface EMG. A Biopac system (Goleta, CA, USA) processed the EMG signals. A repeated measures analysis of variance (ANOVA) determined any difference in the root mean square values and Bonferroni comparisons were used to clarify the order of differences (P<0.05). RESULTS: For the RA, all exercises on the CoreMaster produced significantly higher EMG values compared to the conventional TL. For the EO, TRCM elicited the highest EMG values. However, no significant difference was found for EO between TROK and TRLLCM. CONCLUSION: The CoreMaster elicited a greater challenge to the RA. For the EO, the CoreMaster yielded optimal effects for exercises that required pronounced rotation.