ABSTRACT
Immersion is considered to facilitate exercise-based rehabilitation. However, the drag effect of moving limbs in water, likely to increase the respiratory requirements at exercise, is not mentioned in many reports. The energetic and ventilatory requirements of 30 min steady state cycling exercise performed by healthy male subjects in air and during immersion up to the xiphoid in 33 degrees C water were compared. In the first experimental series nine subjects exercised at the same 60% maximal oxygen consumption (V'O2,max) in air and water. In the two ambient conditions, ventilatory variables had similar values, but the ergometric setting had to be reduced during water immersion so that the workload rated only 69+/-20 W (mean+/-SD) in water versus 121+/-32 W (p<0.001) in air. In the second experimental series, the same ergometric work load (122 W) was achieved by nine subjects with an average V'O2 of 2,210+/-300 mL x min(-1) in air versus 2,868+/-268 mL x min(-1) in water (p<0.001). Resting water immersion caused a marked trend for decreasing vital capacity (p=0.06), but no modification of other ventilatory variables. During exercise at similar V'O2, the average values of minute ventilation (V'E), tidal volume (VT), respiratory frequency (fR), tidal inspiratory time (VT/tI) were not different between water and air. However, at similar ergometric workload, V'E, VT, fR, VT/tI and plasma lactate levels were significantly higher in water than in air. Such consequences of the drag effect of water upon limb movements have not been reported in previous studies relying on shorter exercise bouts. Thus, maintaining steady exercise levels in water either led to a decrease in the workload or required a 25% higher oxygen consumption than in air. These findings may be relevant to the prescription of water immersion rehabilitation programmes.
Subject(s)
Exercise/physiology , Immersion/physiopathology , Oxygen Consumption/physiology , Pulmonary Ventilation/physiology , Adult , Exercise Test , Exercise Therapy , Exercise Tolerance , Humans , Male , Time FactorsABSTRACT
INTRODUCTION: Methylisothiazolinone chloride (Kathon CG) and its derivatives, used as preservatives in cosmetics, have been shown to be allergenic when used in humans although preliminary studies in Guinea pigs failed to reveal any sensitization. Dibromodicyanobutane, associated with phenoxyethanol in Euxyl K400, has been proposed to replace the isothiazolinone derivatives in cosmetics. Preliminary study has shown that these thiazolinone derivatives are not allergenic in Euxyl K400. The similarity of these situations led us to hypothesize that dibromodicyanobutane could become allergenic. METHODS: We tested 0.1 p. 100 dibromodicyanobutane in vaseline in the additional battery of the ICDRG battery in patients with contact eczema. Among the 310 patients tested, 1.94 p. 100 had a positive test for this allergen (during this same period, 1.29 p. 100 of the patients were positive for isothiazolinones). Three patients were hospitalized because of generalized eczema and 1 patient had changed occupation with no effect because the crems containing the allergen had not been avoided. CONCLUSION: Dibromodicyanobutane is a new allergen. Numerous cases of allergy have developed as use of the product becomes more widespread. The consequences of this sensitization may have an economic impact. Animal experimentation has been unable to predict this allergenic effect. Cosmetic products must be precisely labeled with a single international term for each specific molecule and the name of the preservative added to the active substance.
