No abstract

This study examines the response of the exhaled nitric oxide (NO) concentration (CNO) and the exhaled NO output (VNO) during incremental exercise and during recovery in six sedentary women, seven sedentary men, and eight trained men. The protocol consisted of increasing the exercise intensity by 30 W every 3 min until exhaustion, followed by 5 min of recovery. Minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production, heart rate, CNO, and VNO were measured continuously. The CNO in exhaled air decreased significantly provided that the exercise intensity exceeded 65% of the peak VO2. It reached similar values, at exhaustion, in all three groups. The VNO increased proportionally with exercise intensity up to exhaustion and decreased rapidly during recovery. At exhaustion, the mean values were significantly higher for trained men than for sedentary men and sedentary women. During exercise, VNO correlates well with VO2, carbon dioxide production, VE, and heart rate. For the same submaximal intensity, and thus a given VO2 and probably a similar cardiac output, VNO appeared to be similar in all three groups, even if the VE was different. These results suggest that, during exercise, VNO is mainly related to the magnitude of aerobic metabolism and that this relationship is not affected by gender differences or by noticeable differences in the level of physical training.

The aim of this study was to determine whether the power output associated with a maximal lactate steady state (MLSS) (.W(MLSS)) can be assessed using a single incremental cycling test. Eleven recreational sportsmen (age: 22+/-1 years, height: 175+/-6 cm, weight: 71+/-5 kg) volunteered to participate in the study. For each subject the first and second ventilatory thresholds (VT(1) and VT(2), respectively) and the power output corresponding to (respiratory exchange ratio) RER=1.00 were determined during an incremental test to exhaustion. Thereafter, each subject performed several 30-min constant load tests to determine MLSS. The workload used in the first constant test was set to the .W(RER=1.00) determined during the incremental test. .W(VT1) (175+/-24 W) and .W(VT2) (265+/-31 W) were significantly different from .W(MLSS )(220+/-36 W). Whereas, .W(RER=1.00) (224+/-33 W) was similar to .W(MLSS). HR, RER and .VE were significantly different between the 10th and the 30th minutes when exercising at .W(RER=1.00) and at .W(MLSS). In contrast, .VO(2) and .VCO(2) were stable over those 30-min constant tests. Power output at VT(1), RER=1.00 and VT(2) were all correlated to .W(MLSS) but the relationship was stronger between RER=1.00 and MLSS (R (2)=0.95). The present study shows that the power output associated with a RER value equal to 1.00 during an incremental test does not differ from that determined for MLSS. Hence, the MLSS can be estimated with a single exercise test.

Objective. To assess quadriceps strength and fatigability by using femoral nerve magnetic stimulation (FNMS) and their relationship to exercise capacity in patients with fibromyalgia syndrome (FMS) and healthy controls. Methods. Twenty-two women (11 with FMS, 11 controls) performed a maximal incremental cycling test and a quadriceps fatigue test on 2 separate visits. For quadriceps assessment, we used FNMS during and after maximum voluntary contraction (MVC) to evaluate central and peripheral factors of neuromuscular fatigue. Subjects performed sets of 10 intermittent (5 seconds on/5 seconds off ) isometric contractions starting at 10% MVC, in 10% MVC increments from one set to another until exhaustion. Neuromuscular fatigue was assessed with FNMS after each set. Results. FMS patients had reduced initial MVC compared to controls (mean ؎ SD 102 ؎ 18 versus 120 ؎ 24 Nm; P < 0.05) without significant impairment of voluntary activation (mean ؎ SD 93.5% ؎ 3.0% versus 93.1% ؎ 3.4%; P ‫؍‬ 0.74). During the fatigue task, FMS patients exhibited a greater fall in evoked muscular responses (mean ؎ SD ؊26% ؎ 6% versus ؊16% ؎ 8% at set 50% MVC; P < 0.05), but not in MVC (mean ؎ SD ؊24% ؎ 7% versus ؊19% ؎ 4% at set 50% MVC; P ‫؍‬ 0.12). During the cycling test, FMS patients had lowered maximal exercise capacity and an enhanced rate of perceived exertion (RPE) compared to controls. The percent reduction in evoked muscular responses during the quadriceps fatigue test correlated with maximum oxygen consumption (r ‫؍‬ 0.56, P < 0.05) and RPE at submaximal intensity (r ‫؍‬ 0.84, P < 0.05) during cycling. Conclusion. Greater impairment in muscle contractility is associated with enhanced perception of exertion and reduced maximal exercise capacity in FMS patients. Neuromuscular impairments should be considered as an important factor underlying functional limitations in FMS patients.