Physiological responses to self-paced exercise: effort-matched comparisons across running and rowing modalities.

AIM: The purpose of this study was to examine whether or not physiological responses to self-pacing are similar across different exercise modalities where the rating of perceived exertion (RPE) is matched. METHODS: Ten recreationally active adult male subjects completed baseline tests of peak oxygen uptake (.VO2) and subsequently on two separate occasions performed 20-min exercise bouts at RPE 15 (Hard) on both a motorized treadmill and a rowing ergometer. RESULTS: Mean relative work intensity (% of baseline peak (.VO2) for treadmill running was significantly higher than for rowing (86.1% vs. 83.7%) (P<0.05). Mean heart rates (174.7±5.9 vs. 165.5±6.6 b∙min-1) and pre- to post-bout changes in blood lactate concentration (4.0±0.8 vs. 3.3±1.2 mmol/L) were also greater in the running trial than rowing (P<0.05). Baseline peak (.VO2 was positively correlated between modalities (r=0.63; P<0.05) as were the main trial mean (.VO2 (r=0.73; P<0.05) and heart rate (r=0.67; P<0.05) from the 20-min bouts. CONCLUSION: The elevated relative exercise intensity and physiological responses to motorized treadmill running suggests greater work outputs can be accomplished in this modality for the same perceived effort compared to rowing among recreationally active participants.

Self-paced exercise is less physically challenging than enforced constant pace exercise of the same intensity: influence of complex central metabolic control.

OBJECTIVE: To examine whether self-pacing reduces the physiological challenge of performing 5000 m rowing ergometry exercise in comparison with a matched-intensity exercise condition in which a constant effort pacing strategy is enforced. METHODS: Nine healthy well-trained male participants volunteered to participate in three 5000 m rowing conditions (two submaximal and one maximal conditions) in an individualised order. In the submaximal conditions, participants were required to (1) perform 5000 m at a constant rating of perceived exertion (RPE 15-Hard) (SubRPE) or (2) perform 5000 m at an enforced constant pace equivalent to the mean power output (PO) of the SubRPE condition (SubEXT). A maximal condition (MaxTT) was included to disguise the purpose of the study and to facilitate an element of randomisation in the test sequence. Dynamic intratest responses were assessed every 30 s: PO, VO2, iEMG, core (Tc) and skin temperatures (Tsk). RESULTS: There was no difference between performance times of the two submaximal trials. The mean PO represented 83.83 (SD 8.88)% (SubRPE) and 83.40 (8.84)% (SubEXT) of the mean MaxTT power output. Tc (SubRPE:38.46 (0.23) degrees C, SubEXT:38.72 (0.36) degrees C; p<0.01), post-test BLa (SubRPE:5.24 (2.18), SubEXT:6.19 (2.51) mmol/l; p<0.05) and iEMG (p<0.05) were significantly elevated in SubEXT compared with SubRPE. There were no differences in the dynamics of HR or VO2 between SubEXT and SubRPE. The intratest stroke-to-stroke variability of power output was significantly greater in the SubRPE condition compared with SubEXT (p<0.01). CONCLUSIONS: Enforced constant paced exercise presents a significantly greater physiological challenge than self-paced exercise. The ability to dynamically self-pace effort via manipulations of power output during exercise is an important behavioural response to homeostatic challenges and thus forms an integral part of a complex central regulatory process.

Tricobezoar. Reporte de un caso. / Trichobezoar. Report of a case

Se reporta un caso de tricobezoar gastrico en una joven de 19 anos, diagnosticado despues de un parto y tratado quirurgicamente. Es una patologia digestiva poco frecuente, pero en la que hay que pensar en casos de tumor gastrico y obstruccion intestinal, predominantemente en mujeres jovenes con problemas psicopatologicos. Se hace una revision de los puntos de mayor interes