Inter-Individual Variability in the Adaptive Responses to Endurance and Sprint Interval Training: A Randomized...

Area of Science:

• Exercise Physiology
• Sports Science
• Human Adaptation

Background:

• Individual variability in response to exercise training is a significant factor in exercise prescription.
• Understanding the differential adaptive responses to various training modalities is crucial for optimizing fitness outcomes.

Purpose of the Study:

• To investigate and compare the individual adaptive responses to endurance training (END) and sprint interval training (SIT) in recreationally active adults.
• To identify the incidence of non-response to both END and SIT protocols and examine the variability in individual responses.

Main Methods:

• A randomized crossover design was employed with 21 participants completing three weeks of both END and SIT, separated by a three-month washout period.
• Key physiological variables including VO2peak, lactate threshold, and submaximal heart rate (HR) were measured to assess training adaptations.
• Non-response was defined as changes below two times the typical error of measurement for each variable.

Main Results:

• A main effect of training was observed for VO2peak, lactate threshold, and submaximal HR, but individual responses showed considerable variability.
• Non-responders were identified for all measured variables following both END and SIT, with differing patterns of response between the two protocols.
• All participants demonstrated a response in at least one physiological variable when subjected to both training types.

Conclusions:

• The adaptive response to exercise training is highly individual and dependent on the specific training protocol (END vs. SIT).
• The incidence of exercise non-response may be reduced by altering the training stimulus, highlighting the importance of personalized exercise prescription.