Oxygen Uptake, Heart Rate, and Lactate Responses for Continuous Forward Running and Stop-and-Go Running With and Without Directional Changes

Speed Effects on the Accuracy of Heart Rate as Oxygen-Uptake Indicator in Short-Distance Shuttle Running

Purpose: Despite the accuracy of heart rate (HR) as an indicator of the aerobic engagement has been evaluated in several intermittent on-court activities, its validity as an oxygen uptake (V ˙ O 2 ) indicator during shuttle running over short paths remains uncertain. Moreover, it is unclear whether speed may affect such validity. This study evaluated the HR ability in estimating the V ˙ O 2 during 5-m shuttle running at different speeds. Methods: V ˙ O 2 and HR of 12 physically active young men were recorded during an incremental forward running (FW) protocol and a 5-m shuttle test at 50%, 60%, and 75% of maximal aerobic speed (MAS). Slope and intercept of the relationship between HR and V ˙ O 2 (HR/V ˙ O 2 ) were individually determined, in both protocols. The HR measured during the shuttle test was used in the FW HR/V ˙ O 2 to estimate V ˙ O 2 at each shuttle speed. A paired Student's t-test compared slopes and intercepts of the two HR/V ˙ O 2 . A two-way RM-ANOVA and an equality test examined, respectively, the differences and the equality between measured and estimated V ˙ O 2 . Lastly, a Bland-Altman plot described the accuracy and precision of the estimated V ˙ O 2 at each shuttle intensity. Results: Slopes and intercepts of the HR/V ˙ O 2 appeared not different between FW and shuttle running. At 50%MAS, HR underestimated the V ˙ O 2 (~7%), whereas returned accurate values at the two higher velocities, although with high variability (±18%). Conclusions: When using HR as V ˙ O 2 indicator during shuttle running over short paths, a separated analysis of the HR validity as V ˙ O 2 indicator is recommended especially when administering different exercise intensities.

Energy cost differences between marathon runners and soccer players: Constant versus shuttle running

Purpose: In the last decades, the energy cost assessment provided new insight on shuttle or constant running as training modalities. No study, though, quantified the benefit of constant/shuttle running in soccer-players and runners. Therefore, the aim of this study was to clarify if marathon runners and soccer players present specific energy cost values related to their training experience performing constant and shuttle running. Methods: To this aim, eight runners (age 34 ± 7.30y; training experience 5.70 ± 0.84y) and eight soccer-players (age 18.38 ± 0.52y; training experience 5.75 ± 1.84y) were assessed randomly for 6' on shuttle-running or constant-running with 3 days of recovery in-between. For each condition, the blood lactate (BL) and the energy cost of constant (C_r) and shuttle running (C_Sh) was determined. To assess differences for metabolic demand in terms of C_r, C_Sh and BL over the two running conditions on the two groups a MANOVA was used. Results: V·O_2max were 67.9 ± 4.5 and 56.8 ± 4.3 ml·min^-1 kg^-1 (p = 0.0002) for marathon runners and soccer players, respectively. On constant running, the runners had a lower C_r compared to soccer players (3.86 ± 0.16 J kg^-1m^-1 vs. 4.19 ± 0.26 J kg^-1 m^-1; F = 9.759, respectively; p = 0.007). On shuttle running, runners had a higher C_Sh compared to soccer players (8.66 ± 0.60 J kg^-1 m^-1 vs. 7.86 ± 0.51 J kg^-1 m^-1; F = 8.282, respectively; with p = 0.012). BL on constant running was lower in runners compared to soccer players (1.06 ± 0.07 mmol L^-1 vs. 1.56 ± 0.42 mmol L^-1, respectively; with p = 0.005). Conversely, BL on shuttle running was higher in runners compared to soccer players 7.99 ± 1.49 mmol L^-1 vs. 6.04 ± 1.69 mmol L^-1, respectively; with p = 0.028). Conclusion: The energy cost optimization on constant or shuttle running is strictly related to the sport practiced.

Applicability of Field Aerobic Fitness Tests in Soccer: Which One to Choose?

A desire to make fitness testing cheaper and easier to conduct in a team-sport setting has led to the development of numerous field aerobic fitness tests. This has contributed to a growing confusion among strength and conditioning coaches about which one to use. The main aim of this narrative review was to examine the reliability, validity, sensitivity and usefulness of the commonly used field aerobic fitness tests and to provide practical guidelines for their use in soccer. The University of Montreal track test (UMTT) and Vam Eval test seem the best options for estimation of maximal oxygen uptake (VO_2max) while the highest signal-to-noise ratio of the 30-15 intermittent fitness test (30-15IFT) suggests its superior sensitivity to track changes in fitness. The UMTT and 30-15IFT are the best solutions for prescription of long and short high-intensity interval training sessions, respectively. All field tests mostly present with marginal usefulness, but the smallest worthwhile change for UMTT or Vam Eval test, Yo-YoIRT2 and 30-15IFT are smaller than their stage increment making the improvement of only one stage in the test performance already worthwhile. Strength and conditioning coaches are advised to choose the test based on their specific purpose of testing.