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The physiological response to breath holding includes bradycardia and peripheral vasoconstriction, which contrasts with that of exercise which includes tachycardia and peripheral vasodilation. This raises the question as to what the physiological response is to breath holding during exercise. During low-intensity exercise, the breath holding response of bradycardia and peripheral vasoconstriction prevails over the exercise response of tachycardia and peripheral vasodilation, but nevertheless the exercise may be sustained. Due to the lack of availability of extrinsic oxygen (O 2 ) from the atmosphere during breath holding, the energy demands can be met by increased reliance on intrinsic O 2 stores (i.e., O 2 that was in the body before the breath hold) via increased O 2 extraction at the muscle compared with exercise while breathing, or increased contributions from anaerobic energy systems. During high intensity exercise of short duration, the exercise response may prevail over the breath holding response due to the increased parasympathetic withdrawal and sympathetic drive of higher intensity exercise. If breath holding during high-intensity exercise was sustained for long enough, the breath holding response may eventually overcome the exercise response, although this may be difficult due to the inverse relationship between exercise intensity and breath hold duration.

In this video from the 2022 NSCA National Conference, Chris Bailey discusses monitoring, quantifying, and other relevant research in regard to asymmetries in sport performance.

Great S&C coaches do more than design programs—they lead people to achieve their best and most consistent performances.

Learn about sport science careers and the CPSS certification program​.

The countermovement jump (CMJ) is one of the most used performance assessments in strength and conditioning. Although numerous studies discuss the usability of different metrics in this test, this is often performed within the context of a specific aim. However, to our knowledge, no information currently exists providing practitioners with some over-arching recommendations on which metrics to choose when the purpose of using the test differs. This article discusses how the metrics selected to monitor during CMJ testing may differ when aiming to use it as a proxy for athletic performance, as part of neuromuscular fatigue monitoring, or as part of a test battery for return to performance in injured athletes.

Dr. Tim Suchomel gives the annual Dr. Mike Stone Lecture at the 2021 National Conference and discusses muscular strength in detail, including its effect on performance variables, effective training progressions, and strategies for athletes through the whole training spectrum.