Related Experiment Video
Updated: Nov 6, 2025

A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Physiological responses to maximal 4 s sprint interval cycling using inertial loading: the influence of inter-sprint
Emre Vardarli1, Remzi Satiroglu1, Jacob R Allen1
1Department of Kinesiology and Health Education, Human Performance Laboratory, University of Texas at Austin, One University Station, Austin, TX, 78712, USA.
Purpose:
Interval exercise allows very high-power outputs to be maintained, a key for stimulating training adaptations. The main purpose of this study was to develop a sprint interval protocol that stimulated both anaerobic and aerobic systems while maximizing power output and minimizing fatigue. The secondary goal was to investigate the influence of inter-sprint recovery duration.
Methods:
Sixteen (8 females) participants (age: 23.5 ± 3.4 years, peak oxygen consumption (VO2peak): 45.6 ± 9.2 ml kg-1 min-1) took part in this study. The exercise protocol involved 30 bouts of 4 s maximal cycling sprints using an 'Inertial Load Ergometer'. Recovery durations between sprints of 15, 30 and 45 s were studied in three trials.
Results:
Peak power output (PPO) was maintained while taking 45 and 30 s of recovery, although it was 9% higher (p < 0.05) during 45 vs. 30 s. PPO with 15 s recovery declined 18% (p < 0.05) and then stabilized as did oxygen consumption (72±2% VO2peak) at a level that might reflect the peak rate of ATP-PC resynthesis from oxidative metabolism. The 15-, 30-, and 45 s trials elicited 72, 56, and 49% VO2peak and 86, 80, and 75% of maximal heart rate (all p<0.001). Perceived exertion increased with shorter recovery periods but remained at 12.6-14.7 and never became 'very hard'.
Conclusion:
The present study describes the use of an inertial-load ergometer to accommodate repeated 4 s maximal cycling sprints that elicit 72% VO2peak when the recovery period is 15 s. However, a recovery duration of 15 s was insufficient for the maintenance of power generation.
Trial Registration Number And Date:
NCT04448925, 26 Jun 2020; retrospectively registered to clinicaltrials.gov.
More Related Videos
08:21Non-invasive Assessments of Subjective and Objective Recovery Characteristics Following an Exhaustive Jump Protocol
Published on: June 8, 2017
07:40Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training
Published on: October 10, 2019
Related Concept Videos
Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Muscle Recovery and Fatigue
Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be...
Energy Supply for Muscle Contraction