receptor subtype involved, has made it difficult to identify the precise mechanisms by which caffeine exerts its ergogenic effect. One of the problems with trying to evaluate the mechanisms by which caffeine improves high-intensity endurance performance is that the associated physiological responses are
Mark Glaister and Conor Gissane
Cesar Gallo-Salazar, Juan Del Coso, David Sanz-Rivas and Jaime Fernandez-Fernandez
describe and compare the game activity and physiological responses of young tennis players in a competition with 2 consecutive matches on the same day depending on both the session of play (eg, MOR vs AFT) and the final match outcome (eg, winners vs losers). It was hypothesized that these variables would
Rory Warnock, Owen Jeffries, Stephen Patterson and Mark Waldron
repeated (×3) Wingate cycling performance and associated physiological responses. It was hypothesized that all conditions would enhance performance compared to placebo but that the combined properties of caffeine and taurine would lead to an improved performance and reduced CV response during the
Thomas W. Rowland and Tasha A. Rimany
This study compared aerobic, cardiac, and ventilatory changes in 11 premenarcheal girls ages 9–13 years with those of 13 women ages 20–31 during 40 min of steady-load cycling at an intensity of 63% VO2max. Forty-five percent of the girls were cycling above their ventilatory anaerobic threshold, compared to 77% of the women. Between 10 and 40 min of exercise, mean VO2 increased 8.6% (SD = 3.8) and 8.3% (SD = 6.3) in the girls and women, respectively (p > .05), with no significant differences in rise in body temperature. Pattern and magnitude of ventilatory drift (increased VE and respiratory rate with fall in tidal volume) were similar in the two groups. Likewise, the rise in cardiac output and heart rate (with no change in stroke volume) was not significantly different in the two groups. These findings indicate that physiological responses to prolonged aerobic exercise are both quantitatively and qualitatively similar in girls and young women.
Andrew J. Vogler, Anthony J. Rice and Christopher J. Gore
This study evaluated the validity of ergometer tests against the criterion of on-water rowing and determined the reliability of feld measurements by comparing results between ergometer (ERG) and on-water (OW) tests.
Seven male rowers completed incremental tests on a Concept2 rowing ergometer and in a single scull. Average power output, oxygen consumption (VO2), heart rate (HR), blood lactate concentration (BLa) and distance completed were measured during each ERG and OW workload.
Linear regression between power output and HR, BLa, VO2 and distance allowed submaximal results to be compared between ERG and OW tests at equivalent intensities based on five standard power outputs. Submaximal results were analyzed using repeated measure factorial ANOVAs and maximal data used dependent t tests (P < .05), the magnitude of differences were also classified using effect size analyses. The reliability of repeated measurements was established using Typical Error.
Differences between ERG and OW submaximal results were not statistically significant for power output, HR, BLa, and VO2, but distance completed (P < .001) was higher during the ERG test. However, the magnitude of physiological response differences between the ERG and OW tests varied between individuals. Mean HR at anaerobic threshold showed good agreement between both tests (r = .81), but the standard error of the estimate was 9 beats per minute.
Individual variation in physiological response differences between ERG and OW tests meant that training intensity recommendations from the ERG test were not applicable to on-water training for some rowers, but provided appropriate prescriptions for most athletes.
Craig A. Bridge, Michelle A. Jones and Barry Drust
To investigate the physiological responses and perceived exertion during international Taekwondo competition.
Eight male Taekwondo black belts (mean ± SD, age 22 ± 4 y, body mass 69.4 ± 13.4 kg, height 1.82 ± 0.10 m, competition experience 9 ± 5 y) took part in an international-level Taekwondo competition. Each combat included three 2-min rounds with 30 s of recovery between each round. Heart rate (HR) was recorded at 5-s intervals during each combat. Capillary blood lactate samples were taken from the fingertip 1 min before competition, directly after each round and 1 min after competition. Competitors’ rating of perceived exertion (RPE) was recorded for each round using Borg’s 6-to-20 scale.
HR (round 1: 175 ± 15 to round 3: 187 ± 8 beats·min−1; P < .05), percentage of HR maximum (round 1: 89 ± 8 to round 3: 96 ± 5% HRmax; P < .05), blood lactate (round 1: 7.5 ± 1.6 to round 3: 11.9 ± 2.1 mmol·L-1; P < .05) and RPE (round 1: 11 ± 2 to round 3: 14 ± 2; P < .05; mean ± SD) increased significantly across rounds.
International-level Taekwondo competition elicited near-maximal cardiovascular responses, high blood lactate concentrations, and increases in competitors' RPE across combat. Training should therefore include exercise bouts that sufficiently stimulate both aerobic and anaerobic metabolism.
Jennifer Cumming, Tom Olphin and Michelle Law
The aim of the present study was to examine self-reported psychological states and physiological responses (heart rate) experienced during different motivational general imagery scenarios. Forty competitive athletes wore a standard heart rate monitor and imaged five scripts (mastery, coping, anxiety, psyching up, and relaxation). Following each script, they reported their state anxiety and self-confidence. A significant increase in heart rate from baseline to imagery was found for the anxiety, psyching-up, and coping imagery scripts. Furthermore, the intensity of cognitive and somatic anxiety was greater and perceived as being more debilitative following the anxiety imagery script. The findings support Lang’s (1977, 1979) proposal that images containing response propositions will produce a physiological response (i.e., increase heart rate). Moreover, coping imagery enabled the athletes to simultaneously experience elevated levels of anxiety intensity and thoughts and feelings they perceived as helpful.
Fredric Goss, Robert Robertson, Steve Riechman, Robert Zoeller, Ibrahim Dabayebeh, Niall Moyna, Nicholas Boer, Jennifer Peoples and Kenneth Metz
This investigation evaluated the effect of oral potassium phosphate supplementation on ratings of perceived exertion (RPE) and physiological responses during maximal graded exercise tests (GXT). Eight highly trained endurance runners completed a GXT to anchor the Borg 15-point RPE scale and two double-blind counterbalanced GXTs. Subjects ingested either 4,000 mg · day−1 of phosphate (PHOS) or a placebo (PLA) for 2 days. Two weeks separated GXTs. Phosphate levels obtained immediately prior to the GXTs were greater in PHOS than PLA. No differences between PHOS and PLA were noted for the submaximal and maximal physiological responses. RPE for the overall body were lower during PHOS than PLA at intensities corresponding to 70–80% of V̇O2max. This suggests that oral potassium phosphate supplementation mediates perceived exertion during moderately intense exercise.
Andrew J. Vogler, Anthony J. Rice and Robert T. Withers
The Concept II model C (IIC) rowing ergometer was replaced by the Concept II model D (IID), but the design modifications of the updated ergometer might alter resistance characteristics and rowing technique, thereby potentially influencing ergometer test results. This study evaluated the physiological response to rowing on the IIC and IID ergometers during a submaximal progressive incremental test and maximal-performance time trial.
Eight national-level rowers completed submaximal and maximal tests on the IIC and IID ergometers separated by 48 to 72 h. Physiological responses and calculated blood lactate thresholds (LT1 and LT2) were compared between ergometer models (IIC vs IID) using standardized drag-factor settings.
Power output, oxygen consumption, rowing economy (mL O2 · min−1 · W−1), heart rate, blood lactate concentration, stroke rate, and rating of perceived exertion all displayed similar responses regardless of ergometer model. Calculated physiological values equivalent to LT1 and LT2 were also similar between models, except for blood lactate concentration at LT1, which displayed a small but statistically signifcant difference (P = .02) of 0.2 mmol/L.
The physiological response when rowing on IIC and IID ergometers is nearly identical, and testing can therefore be carried out on either ergometer and the results directly compared.
Stanley P. Sady, Victor L. Katch, Kris Berg and John Villanacci
The extent of individual differences in relative endurance and physiological response was examined in adolescent boys (n=22) and compared to data of prepubescent boys (n = 21) and adult men (n = 21). Subjects performed two (test and retest) relative endurance cycle ergometer tests at an initial rate of 105% V̇O2 max, which they attempted to maintain for 8 minutes. Relative endurance performance was defined as the revolutions for each minute of the test (RPM). There were no differences among groups for the total revolutions turned or the total percent dropoff from the initial rate. All groups had similar patterns for consistency of RPM except for Minute 3. The prepubescent boys exhibited the greatest within-individual variation (Si) for HR, especially after Minute 4 (p<.05). On the average, a greater proportion of the total variability in HR was due to Si in comparison to true individual differences (St) for the prepubescents (47%) than either the adolescents (13%) or the adults (11%). The adolescents had the lowest proportion of total variability in V̇O2 due to Si (adolescents 9%, adults 16%, prepubescents 26%). The data support an earlier hypothesis of a threshold age effect on the stability of individual differences for physiological response during relative endurance exercise. A change may occur during adolescence.