Cost-effectiveness of using recombinant human TSH prior to radioiodine ablation for thyroid cancer, compared with treating patients in a hypothyroid state: the German perspective.

OBJECTIVE: This investigation evaluated the cost-effectiveness of radioiodine remnant ablation following preparation with recombinant human TSH (rhTSH), compared with the standard preparation, whereby patients are rendered hypothyroid. DESIGN: The economic evaluation relates to patients with well differentiated thyroid cancer who have undergone thyroidectomy, but have no metastases. The evaluation takes a societal perspective, considering costs and benefits to all parties. The benefits were expressed in units of quality-adjusted life years (QALY), so differences in life expectancy were captured with consideration of quality of life. METHODS: A lifetime Markov model with Monte Carlo simulation of 100,000 patients was used to assess cost per QALY gained. The clinical inputs were sourced from a multi-centre, randomised controlled trial comparing remnant ablation success after rhTSH-preparation with hypothyroid preparation. The model applied German unit costs, however, the structure is generalisable to other jurisdictions. The additional cost of rhTSH procurement and administration is considered relative to the clinical benefits and cost offsets. These included avoidance of hypothyroidism, increased work productivity, earlier discharge from radioprotection and a theoretical reduction in the risk of secondary malignancy. The latter two benefits relate to faster radioiodine clearance after rhTSH preparation. RESULTS: The additional benefits of rhTSH (0.0495 QALY) are obtained with an incremental societal cost of 47 euro, equating to an incremental cost per QALYof 958 euro. Sensitivity analyses had only a modest impact upon cost-effectiveness, with all one-way sensitivity results remaining under 15,000 euro/QALY. CONCLUSIONS: The use of rhTSH prior to radioiodine ablation represents good value-for-money with the benefits to patient and society obtained at modest net cost.

African runners exhibit greater fatigue resistance, lower lactate accumulation, and higher oxidative enzyme activity.

Nine African and eight Caucasian 10-km runners resident at sea level volunteered. Maximal O2 consumption and peak treadmill velocity (PTV) were measured by using a progressive test, and fatigue resistance [time to fatigue (TTF)] was measured by using a newly developed high-intensity running test: 5 min at 72, 80, and 88% of individual PTV followed by 92% PTV to exhaustion. Skeletal muscle enzyme activities were determined in 12 runners and 12 sedentary control subjects. In a comparison of African and Caucasian runners, mean 10-km race time, maximal O2 consumption, and PTV were similar. In African runners, TTF was 21% longer (P < 0.01), plasma lactate accumulation after 5 min at 88% PTV was 38% lower (P < 0.05), and citrate synthase activity was 50% higher (27.9 +/- 7.5 vs. 18.6 +/- 2.1 micromol. g wet wt-1. min-1, P = 0.02). Africans accumulated lactate at a slower rate with increasing exercise intensity (P < 0.05). Among the entire group of runners, a higher citrate synthase activity was associated with a longer TTF (r = 0.70, P < 0.05), a lower plasma lactate accumulation (r = -0.73, P = 0.01), and a lower respiratory exchange ratio (r = -0.63, P < 0.05). We conclude that the African and Caucasian runners in the present study differed with respect to oxidative enzyme activity, rate of lactate accumulation, and their ability to sustain high-intensity endurance exercise.

Running economy of African and Caucasian distance runners.

PURPOSE: Anecdotal evidence suggests an advantageous physiological endowment of the African endurance athlete. Higher fractional utilization of VO2max has been suggested but not measured directly, and investigations of running economy have been inconclusive. The aim of the current study was to measure a) running economy and b) fractional utilization of VO2max, in African and Caucasian 10-km runners of similar body mass. METHODS: Eight African and eight Caucasian runners had no significant difference in mean race time (32.8 +/- 2.8, 32.0 +/- 2.5 min, respectively), body mass (61.4 +/- 7.0, 64.9 +/- 3.0 kg), age, body fat, or lean thigh volume. Caucasian runners were 6 cm taller (P < 0.05). Subjects completed a progressive treadmill VO2peak test. On a separate day, subjects completed two 6-min workloads (16.1 km x h(-1) and 10-km race pace) separated by 5 min. RESULTS: Mean VO2peak was 13% lower in the Africans (61.9 +/- 6.9, 69.9 +/- 5.4 mL x kg(-1) x min(-1), P = 0.01). At 16.1 km x h(-1), the Africans were 5% more economical (47.3 +/- 3.2, 49.9 +/- 2.4 mL x kg(-1) x min(-1), P < 0.05). This difference increased to 8% (P < 0.01) when standardized per kg(0.66). At race pace, the Africans utilized a higher %VO2peak (92.2 +/- 3.7, 86.0 +/- 4.8%, P < 0.01) and had higher HR (185 +/- 9, 174 +/- 11 b x min(-1), P < 0.05) and plasma [ammonia] (113.2 +/- 51, 60.3 +/- 16.9 micromol x L(-1), P < 0.05). Despite the higher relative workload, the plasma [lactate] was not different (5.2 +/- 2.0, 4.2 +/- 1.7 mmol x L(-1), NS). CONCLUSIONS: This study indicates greater running economy and higher fractional utilization of VO2peak in African distance runners. Although not elucidating the origin of these differences, the findings may partially explain the success of African runners at the elite level.

Optimal time of arrival for performance at moderate altitude (1700 m).

PURPOSE: The time course of physiological exercise responses after acute ascent to moderate altitude was investigated. METHODS: Fifteen young male subjects (16.5 +/- 0.8 yr) completed one familiarization and then two further sea level sessions to determine sea level values (SL). Subjects were then tested 6 h (ALT1), 18 h (ALT2), and 47 h (ALT3) after arrival at 1700 m. Subjects completed a 5-min submaximal cycle test, shuttle run test, and 45-s repeated push-up test. Hemoglobin (Hb) and hematocrit (Hct) were measured. RESULTS: Cycle test heart rate (HR) was higher at ALT1 than SL (182 +/- 15 vs 177 +/- 16 b.min(-1), P < 0.01) but had returned to 177 +/- 13 and 176 +/- 12 b.min(-1) at ALT2 and ALT3, respectively. At ALT1, only five subjects completed the full 5 min. Postexercise plasma lactate was not different. Shuttle test HR was higher at ALT1 than SL (191 +/- 8 vs 185 +/- 14 b.min(-1), P = 0.01) but had returned to 185 +/- 10 and 183 +/- 16 b.min(-1) at ALT2 and ALT3. Shuttle run time (SRT) was 37% shorter at ALT1 than SL (251 +/- 134 vs 401 +/- 115 s, P < 0.001) and remained impaired at ALT2 and ALT3 (330 +/- 124 and 344 +/- 115 s, both P < 0.001 vs SL). There was a significant relationship between magnitude of increased HR and reduction in SRT between SL and ALT1 (r = 0.52, P < 0.05). Push-up HR, Hb, and Hct were not affected by altitude. CONCLUSIONS: These findings indicate that detrimental effects of acute ascent to 1700 m on exercise performance are greater after 6 h than after 18 or 47 h. Performance was not entirely restored to SL values even after 47 h, despite restoration of easily measured physiological parameters. The results suggest travel to moderate altitude should occur as early as is practical before competition.

Physical activity of asthmatic and nonasthmatic children.

Questionnaires examining behaviors and attitudes related to physical activity and asthma were administered to 408 urban schoolchildren aged 11-13 years. Asthmatics (16% of the sample) were more frequently active and were more anxious prior to exercise than nonasthmatics, but did not differ significantly from nonasthmatics in enjoyment of exercise or in physical self-concept. The motives for performing exercise or sport were similar in the two groups, although the asthmatics perceived less pressure to be active from parents or school than the nonasthmatics. It is concluded that asthmatic children have favorable behaviors and attitudes in relation to exercise and sport.

Skeletal muscle buffering capacity is higher in the superficial vastus than in the soleus of spontaneously running rats.

Skeletal muscle buffering capacity (beta mtitr) was determined in soleus (type I) and superficial vastus (type II) muscles of 16 Long-Evans rats with differing levels of spontaneous activity and in 11 sedentary control rats. beta mtitr was 24% higher (P < 0.001) in superficial vastus muscle than in soleus muscle (268 +/- 50 vs. 216 +/- 30 mumol H+ g muscle dry wt-1 pH unit-1) (mean +/- SD). There was no relationship between beta mtitr and mean weekly running distance amongst spontaneously running rats, nor was beta mtitr any greater in these rats than in a group of sedentary control rats. Protein to wet wt ratio was 31% higher (P < 0.0001) in the superficial vastus muscle when compared with soleus muscle (22.04 +/- 3.74 vs. 16.77 +/- 3.00 mg protein, 100 mg wet wt muscle-1), but there was no relationship between protein to wet wt ratio and running distance. Initial muscle homogenate pH (pHi) was lower in superficial vastus muscle compared with soleus muscle (6.36 +/- 0.25 vs. 6.63 +/- 0.16). Running rats had a significantly lower pHi in both soleus and superficial vastus than sedentary controls. There was an exponential relationship between weekly running distance and pHi in both the superficial vastus muscle (r = -0.86. P < 0.001) and the soleus muscle (r = -0.73, P < 0.01). Citrate synthase activity correlated with weekly running distance in superficial vastus muscle (r = 0.66, P < 0.01) but not in soleus muscle. The results confirm a higher beta mtitr in the type II superficial vastus muscle when compared with the predominantly type I soleus muscle. We suggest that this may be partly the result of a higher protein concentration in type II muscle. Future studies measuring beta mtitr in mixed muscle (e.g. human vastus lateralis) should report fibre type composition.

Effects of electrical stimulation leg training during the acute phase of spinal cord injury: a pilot study.

Four individuals with a spinal cord injury underwent 16 weeks of isometric electrical stimulation training to both legs for 60 min, five times per week during the first 5 months after injury, while two SCI individuals remained untrained. A baseline biopsy sample of the vastus lateralis muscle was obtained within 1 month of injury, and another biopsy sample was taken after a further 16 weeks. The untrained, paralyzed skeletal muscle displayed a reduction in (1) type I fibers (from 50% to 9%), (2) myosin heavy chain (MHC) I (from 27% to 6%), and (3) fiber cross-sectional area of type I, type IIA and type IIX fibers (-62%, -68%, and -55%, respectively) when compared to the baseline sample of muscle taken within 1 month of injury. In contrast, the trained group showed smaller alterations in type I fibers (from 49% to 40%) and MHC I composition (from 39% to 25%), while fiber cross-sectional area was similar to baseline levels for type I, type IIA and type IIX fibers (-3%, -8%, and -4%, respectively). In conclusion, electrical stimulation training can largely prevent the adverse effects of a spinal cord injury upon paralyzed human skeletal muscle if applied soon after the injury.

Effects of increased inspired oxygen concentrations on exercise performance in chronic heart failure.

Exercise capacity in patients with stable heart failure may be influenced by prolonged drug treatment or exercise training, but acute interventions are generally thought to have little effect. Cardiorespiratory responses to exercise were studied in 12 consecutive patients with chronic congestive heart failure who underwent serial submaximal and maximal exercise tests at inspired oxygen concentrations of 21% (room air), 30%, and 50%. Mean (SD) exercise duration during progressive testing to maximum exercise capacity was prolonged from 548 (276) s on room air to 632 (285) s on 50% oxygen (p = 0.012). During steady-state exercise at 45 W, oxygen enrichment to 50% was associated with significantly increased arterial oxygen saturation (94.6 [1.9]% to 97.5 [1.3]%), and significantly reduced minute ventilation (36.1 [8.6] l/min to 28.1 [5.9] l/min), cardiac output (7.5 [2.3] l/min to 6.5 [1.9] l/min), and subjective scores for fatigue and breathlessness (13.9 [3.1] to 11.5 [3.5]) compared with room air intermediate changes were observed with 30% inspired oxygen. Increased inspired oxygen concentrations can improve exercise performance acutely and modify the ventilatory response to exercise in patients with heart failure. Hyperoxia reduces ventilatory response and circulatory demand while maintaining oxygen delivery at a given workload. The potential benefits of increased inspired oxygen concentrations in the treatment of chronic heart failure merit further assessment.

Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists.

Skeletal muscle buffering capacity (beta m), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, submaximal interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption (VO2max) = 66.2 ml.kg-1.min-1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. beta m increased from 206.6 (17.9) to 240.4 (34.1) mumol H+.g muscle dw-1.pH-1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF150) and 40-km cycle time trial performance (TT40) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, beta m correlated significantly with TT40 performance before HIT (r = -0.82, P < 0.05) and the relationship between change in beta m and change in TT40 was close to significance (r = -0.74). beta m did not correlate with TF150. These results indicate that beta m may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.