July 11, 2020

Dalton Deprez, BSc. Kinesiology (Hons), MPT Student

College of Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan

This article relates to Dalton’s honours thesis, where he studied the effects of a cluster set configuration on measures of power in sprint athletes under the supervision of Dr. Phil Chilibeck. Dalton will continue his education in the Fall of 2020 at the School of Rehabilitation Science at the University of Saskatchewan, beginning his Masters of Physical Therapy.

Take home message

  • Rest redistribution (RR) involves redistributing the inter-set rest periods of a training protocol within the set to create shorter, more frequent rest periods.
  • The use of RR can maintain movement velocity and power output throughout the latter parts of high repetition sets, but knowledge about the underlying mechanism for this benefit is not well understood.
  • This study aimed to investigate the effects of RR on a concentric knee extension task performed at both slow and fast velocities, as well as exploring the effects of the protocols on muscular contractile properties and muscle oxygenation.

Background 

  • Pregnant women who engage in regular moderate-vigorous physical activity (MVPA) derive significant benefits to maternal and fetal health without evidence of harm. Conversely, a sub-set of women with pre-existing conditions or pregnancy-specific complications, known as contraindications, are advised to avoid MVPA due to concerns of adverse pregnancy outcomes. Contraindications to prenatal exercise have been listed in guidelines for over 30 years; however, most are based on expert opinion only and may be outdated in light of new evidence on the wide-ranging benefits of being active during pregnancy.

How the study was done

  • Sixteen resistance trained men (~24 years) performed 4 different maximal effort, single-limb knee extension protocols: 2 ‘fast’ protocols (360°/s) and 2 ‘slow’ protocols (60°/s) on an isokinetic dynamometer.
  • For each speed, both a traditional set (TS) and rest redistribution (RR) protocol were implemented. The TS protocol consisted of 4 sets of 10 repetitions with 95s of interset rest, while the RR protocol consisted of 20 sets of 2 repetitions with 15s of interset rest.

Measures in this study

  • Muscular performance, assessed through peak torque (PT), total work (TW), and power output (PO).
  • Muscle oxygenation, assessed through total hemoglobin concentration and tissue oxygen saturation using near-infrared spectroscopy.
  • Ratings of perceived exertion (RPE) following every 10 repetitions.

What the researchers found

  • When the average of all 40 repetitions were taken, PT, TW, and PO were similar between RR and TS at both movement velocities. However, the RR with high velocity protocol better maintained PT in latter repetitions when compared to TS.
  • The use of RR led to a quicker and more complete recovery post-exercise, signifying that RR results in lower levels of residual fatigue compared to TS.
  • RR protocols resulted in increased total muscle blood flow and oxygen saturation during exercise compared to TS protocols.
  • RPE was significantly lower during the RR protocols at both speeds when compared to the TS protocols.

Conclusion

  • The implementation of shorter, more frequent rest periods during resistance training can be an effective strategy for maintaining movement velocity, lowering ratings of perceived exertion, and attenuating post-exercise fatigue, especially with high velocity training.

Reference: Tufano, J. J., Omcirk, D., Malecek, J., Pisz, A., Halaj, M., & Scott, B. R. (2020).

Traditional sets versus rest-redistribution: a laboratory-controlled study of a specific cluster set configuration at fast and slow velocities.Applied Physiology, Nutrition, and Metabolism, 45(4), 421-430.
https://www.nrcresearchpress.com/doi/10.1139/apnm-2019-0584#.XtfNLJ5KhQ0