Kjetil L. Høydal

Bio: Kjetil L. Høydal is an academic researcher from Norwegian University of Science and Technology. The author has contributed to research in topics: Medicine & Interval training. The author has an hindex of 3, co-authored 3 publications receiving 1065 citations.

Aerobic high-intensity intervals improve VO2max more than moderate training.

Abstract: HELGERUD, J., K. HKYDAL, E. WANG, T. KARLSEN, P. BERG, M. BJERKAAS, T. SIMONSEN, C. HELGESEN, N. HJORTH, R. BACH, and J. HOFF. Aerobic High-Intensity Intervals Improve VO2max More Than Moderate Training. Med. Sci. Sports Exerc., Vol. 39, No. 4, pp. 665-671, 2007. Purpose: The present study compared the effects of aerobic endurance training at different intensities and with different methods matched for total work and frequency. Responses in maximal oxygen uptake (VO2max), stroke volume of the heart (SV), blood volume, lactate threshold (LT), and running economy (CR) were examined. Methods: Forty healthy, nonsmoking, moderately trained male subjects were randomly assigned to one of four groups:1) long slow distance (70% maximal heart rate; HRmax); 2) lactate threshold (85% HRmax); 3) 15/15 interval running (15 s of running at 90-95% HRmax followed by 15 s of active resting at 70% HRmax); and 4) 4 4 min of interval running (4 min of running at 90-95% HRmax followed by 3 min of active restingat 70% HRmax). All four training protocols resulted in similar total oxygen consumption and were performed 3 dIwk j1 for 8 wk. Results: High-intensity aerobic interval training resulted in significantly increased VO2max compared with long slow distanceandlactate-thresholdtrainingintensities(P G 0.01). The percentage increases for the 15/15 and 4 4 min groups were 5.5 and 7.2%, respectively, reflecting increases in VO2max from 60.5 to 64.4 mLIkg j1 Imin j1 and 55.5 to 60.4 mLIkg j1 Imin j1 . SV increased significantly by approximately 10% after interval training (P G 0.05). Conclusions: High-aerobic intensity endurance interval training is significantly more effective than performing the same total work at either lactate threshold or at 70% HRmax, in improving VO2max. The changes in VO2max correspond with changes in SV, indicating a close link between the two. Key Words: LACTATE THRESHOLD, AEROBIC POWER, 4 4-MIN INTERVALS, 15/15 TRAINING, STROKE VOLUME, BLOOD VOLUME

Interval and strength training in CAD patients

Abstract: This study sought to study the effect of high intensity aerobic interval endurance training on peak stroke volume and maximal strength training on mechanical efficiency in coronary artery disease (CAD) patients. 8 CAD patients (age 61.4 ± 3.7 years) trained 30 interval training sessions with 4 × 4 min intervals at 85-95% of peak heart rate while 10 CAD patients (age 66.5 ± 5.5 years) trained 24 sessions of maximal horizontal leg press. In the interval training group peak stroke volume increased significantly by 23% from 94.1 ± 23.0 mL · beat (-1) to 115.8 ± 22.4 mL · beat (-1) (p<0.05). Peak oxygen uptake increased significantly by 17% from 27.2 ± 4.5 mL · kg (-1) · min (-1) to 31.8 ± 5.0 mL · kg (-1) min (-1) (p<0.05) in the same group. In contrast, there was no such exercise training-induced change in peak stroke volume or peak oxygen uptake in the maximal strength training group, despite a 35% improvement in sub maximal walking performance.

Patients with coronary artery- or chronic obstructive pulmonary disease walk with mechanical inefficiency.

Abstract: Objective. Patients with chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD) are associated with exercise intolerance. Whether exercise intolerance and reduced mechanical efficiency are due to inactivity alone or to disease related muscular abnormalities is not clear. The aim was to find out whether two patient groups with different limitations for exercise had the same mechanical inefficiency. Design. CAD and COPD patients were compared to a healthy age matched reference group in walking and cycling mechanical efficiency. Results. Both patient groups showed a similar mechanical inefficiency when walking (COPD 16.9±6.4%, CAD 19.2±4.1%) compared to healthy controls (24.7±6.4%). No differences were found when bicycling. VO2peak (mL·kg−1·min−1) was significantly reduced in both patient groups compared to the healthy controls (COPD=23.1±5.3, CAD=27.9±3.6, Healthy controls=36.2±7.1). Conclusion. Both COPD and CAD patients show mechanical inefficiencies when walking compared to health...

Weight-Based Victimization and Physical Activity Among Adolescents With Overweight or Obesity: A Scoping Review of Quantitative and Qualitative Evidence

Abstract: Background Increased physical activity engagement plays a vital role in preventing and treating overweight or obesity in children and adolescents. Research has found that adolescents who are overweight or obese tend to participate in less physical activity than adolescents of average weight. Weight-based victimization (victimization related to weight or body size) is highly prevalent in adolescence and seems to be a factor that might negatively impact engagement in physical activity. This scoping review's objective was to identify the nature and extent of research evidence on links between weight-based victimization and physical activity among community-based or primary health care samples of adolescents who are overweight or obese. Methods Following established scoping review methods, we searched electronic databases PubMed, Web of science, SportDiscuss, and Cinahl from 23 Nov 2020 to 02 Dec 2020. Published studies with community-based or primary health care samples of adolescents who were overweight or obese (aged 13–18 years, Iso-BMI ≥ 25, i.e., age and gender specific percentiles based on specified cut-off value for overweight and obesity) and that were peer-reviewed and published were included in the analysis. Data from the included studies were put into a table and analyzed descriptively and numerically in terms of the extent and nature of the studies. Results After full text review, 12 articles were included, equally distributed in the qualitative and quantitative paradigm. There was a homogeneity of the research designs applied. Articles revealed high frequency of weight-based victimization. Among quantitative studies the reported links between weight-based victimization and physical activity were somewhat mixed, with three studies reporting weight-based victimization to negatively impact physical activity, while three studies report no significant impact. Qualitative studies reported experiences of teasing and bullying by peers, humiliation, and feelings of insecurity about appearance as barriers to engagement in physical activity. Conclusion The empirical evidence on the links between weight-based victimization and physical activity among community-based or primary-health care samples of adolescents who are overweight or obese is sparse. The results revealed a high presence of weight-based victimization in physical activity which seems to act as barriers for activity engagement. There is a need for more research to advance the understanding of the links between weight-based victimization and physical activity among community-based or primary-health care samples of adolescents who are overweight or obese.

The Long-Term Impact of Postoperative Educational Programs on Weight Loss After Roux-en-Y Gastric Bypass

Abstract: Abstract Purpose Roux-en-Y gastric bypass (RYGB) is a well-documented treatment of severe obesity. Attending postoperative educational programs may improve the outcome. The aim of this study was to evaluate whether participation in educational programs lasting 2–3 years after RYGB influences long-term weight loss, weight regain, physical activity, and compliance to multivitamin supplements. Materials and Methods The Bariatric Surgery Observation Study (BAROBS) is a multicenter retrospective, cross-sectional study 10–15 years after primary RYGB. Four hundred and ninety-seven participants answered questions regarding participation in postoperative educational programs. Participants were divided into frequent attendees (FA) and infrequent attendees (IFA) at the educational programs. Results Ten to 15 years after surgery, a total weight loss (TWL) of 23.2 ± 11.6% were seen in the FA group vs 19.5 ± 12.6% in the IFA group, p < 0.001. Percent excess weight loss (%EWL) was 55.7 ± 28.9% vs 46.0 ± 31.1%, p < 0.001. Weight regain in percent of maximal weight loss for the FA was 32.1 ± 32.8% vs IFA 38.4 ± 40.0%, p = 0.052. No difference between the groups in compliance to multivitamin and physical activity. Conclusion Participants with frequent participation in group-based educational programs had better weight loss outcomes 10–15 years after RYGB and tended to have less weight regain. There was no difference between the two groups in participants compliance to recommended multivitamin supplements and physical activity. Graphical abstract

Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory, Musculoskeletal, and Neuromotor Fitness in Apparently Healthy Adults: Guidance for Prescribing Exercise

Abstract: 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.

Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association.

Abstract: Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus, but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes. The purpose of this statement is to review current knowledge related to the association between CRF and health outcomes, increase awareness of the added value of CRF to improve risk prediction, and suggest future directions in research. Although the statement is not intended to be a comprehensive review, critical references that address important advances in the field are highlighted. The underlying premise of this statement is that the addition of CRF for risk classification presents health professionals with unique opportunities to improve patient management and to encourage lifestyle-based strategies designed to reduce cardiovascular risk. These opportunities must be realized to optimize the prevention and treatment of cardiovascular disease and hence meet the American Heart Association's 2020 goals.

Aerobic Interval Training Versus Continuous Moderate Exercise as a Treatment for the Metabolic Syndrome: A Pilot Study

Abstract: BACKGROUND: Individuals with the metabolic syndrome are 3 times more likely to die of heart disease than healthy counterparts. Exercise training reduces several of the symptoms of the syndrome, but ...

High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis.

Abstract: High-intensity interval training (HIT), in a variety of forms, is today one of the most effective means of improving cardiorespiratory and metabolic function and, in turn, the physical performance of athletes. HIT involves repeated short-to-long bouts of rather high-intensity exercise interspersed with recovery periods. For team and racquet sport players, the inclusion of sprints and all-out efforts into HIT programmes has also been shown to be an effective practice. It is believed that an optimal stimulus to elicit both maximal cardiovascular and peripheral adaptations is one where athletes spend at least several minutes per session in their 'red zone,' which generally means reaching at least 90% of their maximal oxygen uptake (VO2max). While use of HIT is not the only approach to improve physiological parameters and performance, there has been a growth in interest by the sport science community for characterizing training protocols that allow athletes to maintain long periods of time above 90% of VO2max (T@VO2max). In addition to T@VO2max, other physiological variables should also be considered to fully characterize the training stimulus when programming HIT, including cardiovascular work, anaerobic glycolytic energy contribution and acute neuromuscular load and musculoskeletal strain. Prescription for HIT consists of the manipulation of up to nine variables, which include the work interval intensity and duration, relief interval intensity and duration, exercise modality, number of repetitions, number of series, as well as the between-series recovery duration and intensity. The manipulation of any of these variables can affect the acute physiological responses to HIT. This article is Part I of a subsequent II-part review and will discuss the different aspects of HIT programming, from work/relief interval manipulation to the selection of exercise mode, using different examples of training cycles from different sports, with continued reference to T@VO2max and cardiovascular responses. Additional programming and periodization considerations will also be discussed with respect to other variables such as anaerobic glycolytic system contribution (as inferred from blood lactate accumulation), neuromuscular load and musculoskeletal strain (Part II).