Proof-of-concept model for instantaneous heart rate-drift correction during low and high exercise exertion

Introduction: This study aimed to model below and above anaerobic threshold exercise-induced heart rate (HR) drift, so that the corrected HR could better represent V ˙ O 2 kinetics during and after the exercise itself. Methods: Fifteen healthy subjects (age: 28 ± 5 years; V ˙ O 2 M a x : 50 ± 8 mL/kg/min; 5 females) underwent a maximal and a 30-min submaximal (80% of the anaerobic threshold) running exercises. A five-stage computational (i.e., delay block, new training impulse-calculation block, Sigmoid correction block, increase block, and decrease block) model was built to account for instantaneous HR, fitness, and age and to onset, increase, and decrease according to the exercise intensity and duration. Results: The area under the curve (AUC) of the hysteresis function, which described the differences in the maximal and submaximal exercise-induced V ˙ O 2 and HR kinetics, was significantly reduced for both maximal (26%) and submaximal (77%) exercises and consequent recoveries. Discussion: In conclusion, this model allowed HR drift instantaneous correction, which could be exploited in the future for more accurate V ˙ O 2 estimations.

Use of Exercise Training to Enhance the Power-Duration Curve: A Systematic Review

ABSTRACT

Hurd, KA, Surges, MP, and Farrell, JW. Use of exercise training to enhance the power-duration curve: a systematic review. J Strength Cond Res 37(3): 733-744, 2023-The power/velocity-duration curve consists of critical power (CP), the highest work rate at which a metabolic steady state can obtained, and W' (e.g., W prime), the finite amount of work that can be performed above CP. Significant associations between CP and performance during endurance sports have been reported resulting in CP becoming a primary outcome for enhancement following exercise training interventions. This review evaluated and summarized the effects of different exercise training methodologies for enhancing CP and respective analogs. A systematic review was conducted with the assistance of a university librarian and in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Ten studies met the criteria for inclusion and were reviewed. Four, 2, 2, 1, and 1 articles included swimming, cycling, resistance training, rowing, and running, respectively. Improvements in CP, and respective analogs, were reported in 3 swimming, 2 cycling, and 1 rowing intervention. In addition, only 2 cycling and 1 swimming intervention used CP, and respective analogs, as an index of intensity for prescribing exercise training, with one cycling and one swimming intervention reporting significant improvements in CP. Multiple exercise training modalities can be used to enhance the power/velocity-duration curve. Significant improvements in CP were often reported with no observed improvements in W' or with slight decreases. Training may need to be periodized in a manner that targets enhancements in either CP or W' but not simultaneously.

Interrater reliability of a customized submaximal cycle ergometer test

PURPOSE

Graded exercise testing (GXTs) is used to determine maximum oxygen uptake ([Formula: see text]). Recently, customized submaximal exercise testing (CSET) completed on both treadmill and cycle ergometry were validated.

METHODS

Interrater reliability of the CSET for cycle ergometry was examined. Thirteen participants (age 31 ± 10.2 y, weight 77.9 ± 10.5 kg, height 176.2 ± 9.9 cm, body mass index 25.1 ± 2.9) completed the 2-stage × 3-min CSET protocol performed by two separate testers. True [Formula: see text] was determined using the highest value derived by a GXT and verification bout. Skeletal muscle oxygen saturation ([Formula: see text]), measured using near-infrared spectrometry on the medial gastrocnemius muscle, and [Formula: see text] were monitored during each CSET; whereby, [Formula: see text] kinetics were modeled breath-by-breath data for each 3-min stage. Measurement agreement was quantified using intraclass coefficient (ICC), typical error (TE), and coefficient of variation (CV).

RESULTS

"True" [Formula: see text] (ml·kg^-1·min^-1) between the GXT (41.3 ± 10.5) and verification (42.5 ± 11.5) was established (ICC = 0.98, TE: 0.98, CV 2.1%). Estimated [Formula: see text] by tester 1 (42.5 ± 9.8) and tester 2 (42.7 ± 8.9) did not differ from "true" [Formula: see text] (F_2,36 = 0.02, p = 0.98, η_p² = 0.00). The second stage evoked a [Formula: see text] slow component of 194 ± 124 ml·min^-1 that corresponded with a time-dependent decline of [Formula: see text]. The mean [Formula: see text] from the two CSET testers were highly correlated (ICC = 0.91, TE: 4.1%, CV = 8.9%).

CONCLUSIONS

The CSET is a reliable and valid procedure and [Formula: see text] is a useful tool for corroborating the second stage is in the heavy-intensity domain.

Validity of a customized submaximal treadmill protocol for determining VO2max

INTRODUCTION

A customized submaximal exercise test for cycle ergometry was reported as a superior estimate of maximum oxygen uptake (VO_2max) in comparison to the traditional YMCA ergometry test.

PURPOSE

Following similar methodology, we sought to validate a customized submaximal treadmill test (CustomTM) compared with the widely used Bruce submaximal protocol.

METHODS

Participants (29 women and 21 men; age = 31.37 ± 11.44 year, BMI = 24.02 ± 3.03) performed a graded exercise test (GXT) with a subsequent exhaustive, square-wave bout for the verification of "true" VO_2max. In counterbalanced order, subjects then completed submaximal protocols. The CustomTM protocol consisted of two 3-min stages estimated at 35 and 70% of VO_2max, where VO_2max was estimated with a linear regression equation utilizing sex, BMI, age, and self-reported physical activity.

RESULTS

VO₂ values from the GXT and verification bout were 47.2 ± 7.7 and 47.0 ± 7.7 ml kg^-1 min^-1, respectively (ICC = 0.99, CV = 2.0%, TE = 0.83 ml kg^-1 min^-1), with the highest value used as "true" VO_2max (47.7 ± 7.7 ml kg^-1 min^-1). Neither the Bruce (45.95 ± 6.97 ml kg^-1 min^-1) nor the CustomTM (47.3 ± 9.4 ml kg^-1 min^-1) protocol differed from "true" VO_2max. The CustomTM had a "very large" measurement agreement with "true" VO_2max (ICC = 0.78, CV of 9.1%, TE = 4.07 ml kg^-1 min^-1). Bruce had a "large" measurement agreement with "true" VO_2max (ICC = 0.62, CV of 10.0%, TE = 4.51 ml kg^-1 min^-1).

CONCLUSION

The CustomTM was superior to the Bruce protocol, because it included a stage below and above gas exchange threshold, yielded a better measurement agreement for "true" VO_2max, and was more time efficient.

Comparison of the YMCA and a Custom Submaximal Exercise Test for Determining VO2max

The maximal oxygen uptake (VO2max) is deemed the highest predictor for all-cause mortality, and therefore, an ability to assess VO2max is important. The YMCA submaximal test is one of the most widely used tests to estimate VO2max; however, it has questionable validity.

PURPOSE

We validated a customized submaximal test that accounts for the nonlinear rise in VO2 relative to power output and compared its accuracy against the YMCA protocol.

METHODS

Fifty-six men and women performed a graded exercise test with a subsequent exhaustive, square wave bout for the verification of "true" VO2max. In counterbalanced order, subjects then completed the YMCA test and our new Mankato submaximal exercise test (MSET). The MSET consisted of a 3-min stage estimated at 35% VO2max and a second 3-min stage estimated at either 65% or 70% VO2max, where VO2max was estimated with a regression equation using sex, body mass index, age, and self-reported PA-R.

RESULTS

VO2 values from the graded exercise test and square wave verification bout did not differ with the highest value used to identify "true" VO2max (45.1 ± 8.89 mL · kg(-1) · min(-1)). The MSET (43.6 ± 8.6 mL · kg(-1) · min(-1)) did not differ from "true" VO2max, whereas the YMCA test (41.1 ± 9.6 mL · kg(-1) · min(-1)) yielded an underestimation (P = 0.002). The MSET was moderately correlated with "true" VO2max (ICC = 0.73, CV of 11.3%). The YMCA test was poorly correlated with "true" VO2max (ICC = 0.29, CV of 15.1%).

CONCLUSIONS

To our knowledge, this is the first study to examine submaximal exercise protocols versus a verified VO2max protocol. The MSET yielded better estimates of VO2max because of the protocol including a stage exceeding gas exchange threshold.

American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise

The purpose of this Position Stand is to provide guidance to professionals who counsel and prescribe individualized exercise to apparently healthy adults of all ages. These recommendations also may apply to adults with certain chronic diseases or disabilities, when appropriately evaluated and advised by a health professional. This document supersedes the 1998 American College of Sports Medicine (ACSM) Position Stand, "The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Healthy Adults." The scientific evidence demonstrating the beneficial effects of exercise is indisputable, and the benefits of exercise far outweigh the risks in most adults. A program of regular exercise that includes cardiorespiratory, resistance, flexibility, and neuromotor exercise training beyond activities of daily living to improve and maintain physical fitness and health is essential for most adults. The ACSM recommends that most adults engage in moderate-intensity cardiorespiratory exercise training for ≥30 min·d on ≥5 d·wk for a total of ≥150 min·wk, vigorous-intensity cardiorespiratory exercise training for ≥20 min·d on ≥3 d·wk (≥75 min·wk), or a combination of moderate- and vigorous-intensity exercise to achieve a total energy expenditure of ≥500-1000 MET·min·wk. On 2-3 d·wk, adults should also perform resistance exercises for each of the major muscle groups, and neuromotor exercise involving balance, agility, and coordination. Crucial to maintaining joint range of movement, completing a series of flexibility exercises for each the major muscle-tendon groups (a total of 60 s per exercise) on ≥2 d·wk is recommended. The exercise program should be modified according to an individual's habitual physical activity, physical function, health status, exercise responses, and stated goals. Adults who are unable or unwilling to meet the exercise targets outlined here still can benefit from engaging in amounts of exercise less than recommended. In addition to exercising regularly, there are health benefits in concurrently reducing total time engaged in sedentary pursuits and also by interspersing frequent, short bouts of standing and physical activity between periods of sedentary activity, even in physically active adults. Behaviorally based exercise interventions, the use of behavior change strategies, supervision by an experienced fitness instructor, and exercise that is pleasant and enjoyable can improve adoption and adherence to prescribed exercise programs. Educating adults about and screening for signs and symptoms of CHD and gradual progression of exercise intensity and volume may reduce the risks of exercise. Consultations with a medical professional and diagnostic exercise testing for CHD are useful when clinically indicated but are not recommended for universal screening to enhance the safety of exercise.