Author(s): GULIN, J., KLARIC, L., VUCETIC, V., Institution: UNIVERSITY OF ZAGREB FACULTY OF KINESIOLOGY, Country: CROATIA, Abstract-ID: 2077

INTRODUCTION:
Accurate information regarding maximal oxygen uptake (VO2max) and the speed at which it is reached (vVO2max) is a prerequisite for the precise prescription of training intensities, particularly in high-intensity interval training, making it vital that the movement modality used during a graded exercise test (GXT) matches the specific modality used in the training sessions. While most VO2max protocols are conducted in the sagittal plane, many athletes frequently, and sometimes predominantly, utilize lateral movements in the frontal plane. This study aimed to determine the criterion validity of a GXT using lateral running on a treadmill compared to the gold standard forward running test, while also assessing the reliability of the lateral protocol through repeated measurements.
METHODS:
The study sample consisted of 17 healthy, physically active males (age 25.27 ± 2.14 years; body height 180.76 ± 5.03 cm; body mass 78.44 ± 7.64 kg). Participants randomly performed one forward running GXT and two lateral running GXTs on a motorized treadmill during three separate laboratory visits. The protocol utilized a modified KF1 protocol, involving a standardized 2-minute walk at 3 km/h, followed by speed increments of 0.5 km/h every 30 seconds until the participant reached exhaustion. The highest VO2 response recorded during a 30-second interval was defined as VO2max. Criterion validity was assessed by comparing the forward and lateral running protocols using a paired t-test and Bland-Altman analysis. Reliability was determined through a test-retest design of the two lateral running trials, evaluated using the same statistical procedures to assess agreement and systematic bias.
RESULTS:
Results indicated a statistically significant difference in VO2max between forward and lateral running (p < 0.01), with the lateral running protocol yielding approximately 7.03 percent lower values (forward: 52.32 ± 5.20 ml/kg/min; lateral: 48.66 ± 5.94 ml/kg/min). Bland-Altman analysis confirmed that the lateral test systematically underestimates VO2max compared to the gold standard (bias -3.66 ml/kg/min, with LoA: -10.10 to 2.77)). However, no significant differences were found between the two lateral running trials (p > 0.05), and the results differed by only 0.6 percent, demonstrating high reliability and reproducibility with comparable conclusions in Bland-Altman analysis (bias: -0,29 ml/kg/min, with LoA: -5.85 to 5.27).
CONCLUSION:
The lower VO2max values observed in lateral running likely stem from the activation of a smaller muscle volume, coordination limits at higher speeds (typically above 11 km/h), and an inability to efficiently utilize elastic energy in the frontal plane. In conclusion, while the lateral running GXT does not meet criterion validity for assessing VO2max compared to forward running, it provides a highly reliable measure for monitoring sport-specific aerobic performance in movements involving the frontal plane.