Jennifer L. Trilk

Bio: Jennifer L. Trilk is an academic researcher from University of South Carolina. The author has contributed to research in topics: Lifestyle medicine & Health care. The author has an hindex of 21, co-authored 45 publications receiving 1268 citations. Previous affiliations of Jennifer L. Trilk include University of Georgia & California State Polytechnic University, Pomona.

Ergogenic effects of low doses of caffeine on cycling performance.

Abstract: The purpose of this experiment was to learn whether low doses of caffeine have ergogenic, perceptual, and metabolic effects during cycling. To determine the effects of 1, 2, and 3 mg/kg caffeine on cycling performance, differentiated ratings of perceived exertion (D-RPE), quadriceps pain intensity, and metabolic responses to cycling exercise, 13 cyclists exercised on a stationary ergometer for 15 min at 80% VO, then, after 4 min of active recovery, completed a 15-min VO2peak performance ride 60 min after ingesting caffeine or placebo. Work done (kJ/kg) during the performance ride was used as a measure of performance. D-RPE, pain ratings, and expired-gas data were obtained every 3 min, and blood lactate concentrations were obtained at 15 and 30 min. Compared with placebo, caffeine doses of 2 and 3 mg/kg increased performance by 4% (95% CI: 1.0-6.8%, p = .02) and 3% (95% CI: -0.4% to 6.8%, p = .077), respectively. These effects were ergogenic, on average, but varied considerably in magnitude among individual cyclists. There were no effects of caffeine on D-RPE or pain throughout the cycling task. Selected metabolic variables were affected by caffeine, consistent with its known actions. The authors conclude that caffeine preparations of 2 and 3 mg/kg enhanced performance, but future work should aim to explain the considerable interindividual variability of the drug's ergogenic properties.

Effect of sprint interval training on circulatory function during exercise in sedentary, overweight/obese women.

Abstract: Very high-intensity, low-volume, sprint interval training (SIT) increases muscle oxidative capacity and may increase maximal oxygen uptake ( $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ ), but whether circulatory function is improved, and whether SIT is feasible in overweight/obese women is unknown. To examine the effects of SIT on $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ and circulatory function in sedentary, overweight/obese women. Twenty-eight women with BMI > 25 were randomly assigned to SIT or control (CON) groups. One week before pre-testing, subjects were familarized to $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ testing and the workload that elicited 50% $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ was calculated. Pre- and post-intervention, circulatory function was measured at 50% of the pre-intervention $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ , and a GXT was performed to determine $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ . During the intervention, SIT training was given for 3 days/week for 4 weeks. Training consisted of 4–7, 30-s sprints on a stationary cycle (5% body mass as resistance) with 4 min active recovery between sprints. CON maintained baseline physical activity. Post-intervention, heart rate (HR) was significantly lower and stroke volume (SV) significantly higher in SIT (−8.1 and 11.4%, respectively; P < 0.05) during cycling at 50% $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ ; changes in CON were not significant (3 and −4%, respectively). Changes in cardiac output ( $$ {\dot{\text{Q}}} $$ ) and arteriovenous oxygen content difference [(a − v)O2 diff] were not significantly different for SIT or CON. The increase in $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ by SIT was significantly greater than by CON (12 vs. −1%). Changes by SIT and CON in HRmax (−1 vs. −1%) were not significantly different. Four weeks of SIT improve circulatory function during submaximal exercise and increases $$ {\dot{V}\text{O}}_{{ 2 {\text{max}}}} $$ in sedentary, overweight/obese women.

Caffeinated sports drink: ergogenic effects and possible mechanisms.

Abstract: This double-blind experiment examined the effects of a caffeinated sports drink during prolonged cycling in a warm environment. Sixteen highly trained cyclists completed 3 trials: placebo, carbohydrate-electrolyte sports drink (CES), and caffeinated sports drink (CES+CAF). Subjects cycled for 135 min, alternating between 60% and 75% VO2max every 15 min for the first 120 min, followed by a 15-min performance ride. Maximal voluntary (MVC) and electrically evoked contractile properties of the knee extensors were measured before and after cycling. Work completed during the performance ride was 15-23% greater for CES+CAF than for the other beverages. Ratings of perceived exertion were lower with CES+CAF than with placebo and CES. After cycling, the MVC strength loss was two-thirds less for CES+CAF than for the other beverages (5% vs. 15%). Data from the interpolated-twitch technique indicated that attenuated strength loss with CES+CAF was explained by reduced intrinsic muscle fatigue.

Dietary quercetin supplementation is not ergogenic in untrained men

Abstract: Quercetin supplementation increases muscle oxidative capacity and endurance in mice, but its ergogenic effect in humans has not been established. Our study investigates the effects of short-duratio...

Call to Action on Making Physical Activity Assessment and Prescription a Medical Standard of Care.

Abstract: The U.S. population is plagued by physical inactivity, lack of cardiorespiratory fitness, and sedentary lifestyles, all of which are strongly associated with the emerging epidemic of chronic disease. The time is right to incorporate physical activity assessment and promotion into health care in a manner that engages clinicians and patients. In April 2015, the American College of Sports Medicine and Kaiser Permanente convened a joint consensus meeting of subject matter experts from stakeholder organizations to discuss the development and implementation of a physical activity vital sign (PAVS) to be obtained and recorded at every medical visit for every patient. This statement represents a summary of the discussion, recommendations, and next steps developed during the consensus meeting. Foremost, it is a "call to action" for current and future clinicians and the health care community to implement a PAVS in daily practice with every patient.

Preventing Chronic Diseases: A Vital Investment

Abstract: Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd preventing chronic diseases a vital investment to read.

The Association of American Medical Colleges

Abstract: BIOMEDICAL RESEARCH POLICY COMMITTEE REPORT WAS PUBLISHED AS A SUPPLEMENT TO THE AUGUSTJOURNAL OF MEDICAL EDUCATION. A REPRINT IS ENCLOSED. REQUESTS FOR ADDITIONAL COPIES SHOULD BE ADDRESSED TO THISOFFICE. -COPIES ARE BEING SENT TO MEMBERS OF CONGRESS AND THE KEY MEMBERS OF THE ADMINISTRATION. CALLING UPON-YOUR SENATORSAND CONGRESSMEN TO TELL THE STORY OF THE ROLE. OF MEDICAL SCHOOLS IN BIOMEDICAL RESEARCH AND HEALTH CARE IS IMPORTANT.I STRONGLY URGE THAT YOU MAKE AN 411 APPOINTMENT TO SEE YOUR CONGRESSIONAL REPRESENTATIVES WHILE YOU ARE IN WASHINGTON FOR THE COUNCIL MEETINGON OCTOBER 29. UPON REQUEST WE CAN SUPPLY THE NAMES OF APPOINTMENT SECRETARIES AND PHONE NUMBERS OF YOUR SENATORS AND CONGRESSMEN. APPROPRIATIONS COMMITTEE ACTED WITH EXTRAORDINARY ALACRITY THIS YEAR. THE-NIH APPROPRIATION WAS INCREASED BY 242 MILLION DOLLARSOVER 1971, REPRESENTING A 142 MILLION DOLLAR INCREASE OVER. THE ADMINISTRATION BUDGET, THE BLUE SHEET ASCRIBES APPROPRIATIONS OUTCOME TO THE EFFECTIVENESS OF THE COALITION FOR HEALTH FUNDING UNDER THE LEADERSHIP OF JOHN A. D. COOPER.

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).

High-Intensity Interval Training, Solutions to the Programming Puzzle

Abstract: High-intensity interval training (HIT) is a well-known, time-efficient training method for improving cardiorespiratory and metabolic function and, in turn, physical performance in athletes. HIT involves repeated short (<45 s) to long (2–4 min) bouts of rather high-intensity exercise interspersed with recovery periods (refer to the previously published first part of this review). While athletes have used ‘classical’ HIT formats for nearly a century (e.g. repetitions of 30 s of exercise interspersed with 30 s of rest, or 2–4-min interval repetitions ran at high but still submaximal intensities), there is today a surge of research interest focused on examining the effects of short sprints and all-out efforts, both in the field and in the laboratory. Prescription of HIT consists of the manipulation of at least nine variables (e.g. work interval intensity and duration, relief interval intensity and duration, exercise modality, number of repetitions, number of series, between-series recovery duration and intensity); any of which has a likely effect on the acute physiological response. Manipulating HIT appropriately is important, not only with respect to the expected middle- to long-term physiological and performance adaptations, but also to maximize daily and/or weekly training periodization. Cardiopulmonary responses are typically the first variables to consider when programming HIT (refer to Part I). However, anaerobic glycolytic energy contribution and neuromuscular load should also be considered to maximize the training outcome. Contrasting HIT formats that elicit similar (and maximal) cardiorespiratory responses have been associated with distinctly different anaerobic energy contributions. The high locomotor speed/power requirements of HIT (i.e. ≥95 % of the minimal velocity/power that elicits maximal oxygen uptake [v/p $$ \dot{V} $$ O2max] to 100 % of maximal sprinting speed or power) and the accumulation of high-training volumes at high-exercise intensity (runners can cover up to 6–8 km at v $$ \dot{V} $$ O2max per session) can cause significant strain on the neuromuscular/musculoskeletal system. For athletes training twice a day, and/or in team sport players training a number of metabolic and neuromuscular systems within a weekly microcycle, this added physiological strain should be considered in light of the other physical and technical/tactical sessions, so as to avoid overload and optimize adaptation (i.e. maximize a given training stimulus and minimize musculoskeletal pain and/or injury risk). In this part of the review, the different aspects of HIT programming are discussed, from work/relief interval manipulation to HIT periodization, using different examples of training cycles from different sports, with continued reference to the cardiorespiratory adaptations outlined in Part I, as well as to anaerobic glycolytic contribution and neuromuscular/musculoskeletal load.

Effects of high-intensity interval training on cardiometabolic health: a systematic review and meta-analysis of intervention studies

Abstract: The current review clarifies the cardiometabolic health effects of high-intensity interval training (HIIT) in adults. A systematic search (PubMed) examining HIIT and cardiometabolic health markers was completed on 15 October 2015. Sixty-five intervention studies were included for review and the methodological quality of included studies was assessed using the Downs and Black score. Studies were classified by intervention duration and body mass index classification. Outcomes with at least 5 effect sizes were synthesised using a random-effects meta-analysis of the standardised mean difference (SMD) in cardiometabolic health markers (baseline to postintervention) using Review Manager 5.3. Short-term (ST) HIIT (<12 weeks) significantly improved maximal oxygen uptake (VO2 max; SMD 0.74, 95% CI 0.36 to 1.12; p<0.001), diastolic blood pressure (DBP; SMD −0.52, 95% CI −0.89 to −0.16; p<0.01) and fasting glucose (SMD −0.35, 95% CI −0.62 to −0.09; p<0.01) in overweight/obese populations. Long-term (LT) HIIT (≥12 weeks) significantly improved waist circumference (SMD −0.20, 95% CI −0.38 to −0.01; p<0.05), % body fat (SMD −0.40, 95% CI −0.74 to −0.06; p<0.05), VO2 max (SMD 1.20, 95% CI 0.57 to 1.83; p<0.001), resting heart rate (SMD −0.33, 95% CI −0.56 to −0.09; p<0.01), systolic blood pressure (SMD −0.35, 95% CI −0.60 to −0.09; p<0.01) and DBP (SMD −0.38, 95% CI −0.65 to −0.10; p<0.01) in overweight/obese populations. HIIT demonstrated no effect on insulin, lipid profile, C reactive protein or interleukin 6 in overweight/obese populations. In normal weight populations, ST-HIIT and LT-HIIT significantly improved VO2 max, but no other significant effects were observed. Current evidence suggests that ST-HIIT and LT-HIIT can increase VO2 max and improve some cardiometabolic risk factors in overweight/obese populations.