Author(s): MATOMÄKI, P., Institution: UNIVERSITY OF JYVÄSKYLÄ, Country: FINLAND, Abstract-ID: 336

INTRODUCTION:
Typically, low intensity endurance exercise (LIE) is performed as a continuous session below the first lactate threshold. However, this is not the only way to execute LIE. High intensity micro-intervals, which should not be confused with maximal sprint interval exercises, are exercises, where work phase lasts at most 15 seconds at ~100% VO2max and recovery period is at least twice as long. These intervals mimic LIE metabolically and cardiopulmonarily [1]. The energy during micro-intervals is produced aerobically using oxygen from the myoglobin stores [1, 2]. Therefore, micro-intervals are highly promising stimulus for peripheral aerobic adaptations, as well as for neuromuscular system adaptations, as muscles operates at or near 100% VO2max with minimal anaerobic component and metabolic cost.

However, little is known about the feasibility and usability of such intervals in the long-term training. The aim of the present study was to investigate whether high-level cyclists’ LIE can be replaced with high intensity micro-intervals.

METHODS:
In this quantitative-qualitative pilot study, three national-level cyclists (one female) progressively replaced majority of their LIE with micro-intervals for 10 weeks. They underwent a VO2max test and a 6-minute time trial before and after the intervention. To monitor the stressfulness of the training, they completed total quality recovery -scale [3] each morning. Finally, they were interviewed immediately after the intervention.

RESULTS:
During the 10-week intervention, the cyclists accumulated 12.5–14.0 h (9–14% of all training time) above VO2max intensity, which accounted for 65–99% of the amount they accumulated during the entire year prior. The cyclists became accustomed to micro-intervals and reported neither cumulative fatigue nor a decrease in total quality recovery. 6-min time trial improved 12–27 W (3–7%), while there were no changes in VO2max.

CONCLUSION:
A novel finding was that the extensive use of high intensity micro-intervals is a feasible method for athletes; Micro-intervals do not induce excessive fatigue, they allow athletes to accumulate a large amount of high intensity time, and they provide positive performance adaptations. However, the optimal way to include micro-intervals into training and their role in training programming still need thorough examination.

[1] Åstrand I, et al. Myohemoglobin as an Oxygen‐Store in Man. Acta Physiol Scand. 1960;48(3–4):454–60.
[2] Saltin B & Essen B. Muscle glycogen, lactate, ATP, and CP in intermittent exercise. 1971
[3] Kenttä G & Hassmén P. Overtraining and Recovery A Conceptual Model. Sports Medicine. 1998;26(1):1–16.