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Maintain the same relative intensity for continued training adaptations

Posted on Tuesday, 8 January, 2013 by anthony

Recent research looked at the effect of 10 days of intensified training (HIIT and moderate intensity training) on mitochondrial gene expression and subsequent training adaptations, following training at the same absolute exercise intensity.

The high intensity interval training sessions

The researchers looked at mitochondrial gene expression following four high intensity interval training sessions (6 x 5 minutes at 90-100% VO2max) and six moderate intensity training sessions (45-90minutes at 75% VO2max) over a 10-day training period. Prior to the exercise training subjects performed a 60minute cycle at 164±18 W (72% of pre-training VO2max). The 60minute exercise trial was repeated after the 10-day training period and performed at the same absolute intensity which corresponded with 64% of pre-training VO2max.

What the researchers found

The main finding of the research was that following the training period there was reduced mitochondrial gene expression (PGC-1α mRNA expression) at the same absolute exercise intensity the work intensity was maintained in the second exercise bout however the relative intensity was lower (72% vs. 64% VO2peak pre- and post-training respectively) and indicates the importance of maintaining the same relative intensity for continued training adaptations. Additional findings were that short term intensified training (4 HIIT sessions over a 10-day period) led to increased mitochondrial gene expression and protein abundance.

Practical Implications – as your fitness/performance level increases you should ensure you train at the same relative exercise intensity (e.g. same percentage of maximum heart rate) for continued training adaptations. The best way to do this is to work at a percentage of your maximum heart rate which will help to ensure that as your fitness improves so does your absolute work intensity.


Stepto NK, Benziane B, Wadley GD, Chibalin AV, Canny BJ, et al. (2012) Short-Term Intensified Cycle Training Alters Acute and Chronic Responses of PGC1α and Cytochrome C Oxidase IV to Exercise in Human Skeletal Muscle. PLoS ONE 7(12): e53080. doi:10.1371/journal.pone.0053080

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