Inspiratory muscle adaptations following pressure or flow training in humans

Abstract

Skeletal muscle adapts differently to training with high forces or with high velocities. The effects of these disparate training protocols on the inspiratory muscles were investigated in ten healthy volunteers. Five subjects trained using high force (pressure) loads (pressure trainers) and five trained using high velocity (flow) loads (flow trainers). Pressure training entailed performing 30 maximal static inspiratory efforts against a closed airway. Flow training entailed performing 30 sets of three maximal dynamic inspiratory efforts against a minimal resistance. Training was supervised and carried out 5 days a week for 6 weeks. Inspiratory flow rates and oesophageal pressure-time curves were measured before and after training. Peak inspiratory pressures during maximal static and dynamic efforts and peak flows during the maximal dynamic efforts were calculated. The time-to-peak pressure and rate of rise in peak pressure during maximal static and dynamic manoeuvres were also calculated before and following training. Maximal static pressure increased in the pressure training group and maximal dynamic pressure increased in the flow training group. Both groups increased the rate of pressure production (dP/dt) during their respective maximal efforts. The post-training decrease in time-to-peak pressure was proportionately greater in the flow trainers than in the pressure trainers. The differences in time-to-peak pressure between the two groups were consistent with the different effects of force and velocity training on the time-to-peak tension of skeletal muscle.

Effect of inspiratory muscle training with an intermediate load on inspiratory power output in COPD

“…The main finding was the increase in PO due to a larger V 'I as well as to a reduction in tI and tI/ttot with a normal VT. These results, which are in agreement with data from TZELEPIS et al [16] and BISSCHOP et al [17], suggesting changes in shortening velocity of in-spiratory muscles, allow us to speculate upon structural changes at the level of muscle fibres in response to specific recruitment patterns induced by training.…”

“…In conclusion, the results of the present study, as well as those reported by others in normal subjects [3,16] suggest that the use of moderate loads to train inspiratory muscles elicits improvements in both strength and shortening velocity and thus, in power output. We believe that in patients with chronic obstructive pulmonary disease, these outcomes are more relevant for coping with the increased ventilatory demands of daily life activities, than the improvement in strength alone achieved by training with high pressure loads [1].…”

“…The effect of IMT with either flow or pressure as a target load has recently been studied by TZELEPIS et al [16] in normal subjects. They found that flow-targeted training diminished the time to reach the peak oesophageal pressure by about 25%, when performing maximal inspiratory efforts.…”

Pulmonary adaptations to swim and inspiratory muscle training

“…There is very little information on the effect of inspiratory muscle conditioning on inspiratory flow, and thus on inspiratory muscle PO. As with other skeletal muscles, it has been shown that the inspiratory muscles can be trained to increase their capacity to generate force (pressure) or muscle shortening velocity (flow) (Leith and Bradley 1976;Tzelepis et al 1999;Tzelepis et al 1994). During swimming (flow-targeted type training) a higher tidal volume may cause encroachment on end-inspiratory reserve volume, which requires the inspiratory muscles to shorten at a high velocity during the rapid inspiration as the face leaves the water (Cordain and Stager 1988;Fanta et al 1983).…”

“…During swimming (flow-targeted type training) a higher tidal volume may cause encroachment on end-inspiratory reserve volume, which requires the inspiratory muscles to shorten at a high velocity during the rapid inspiration as the face leaves the water (Cordain and Stager 1988;Fanta et al 1983). Tzelepis et al (Tzelepis et al 1999) found that flow-targeted training diminished the time to reach the peak oesophageal pressure by about 25%, when performing IMT. Thus, during swimming, it is feasible that the enhanced airway resistive load due to high flow rates during inspiration and expiration (Courteix et al 1997;Kohl et al 1997) increases strength and shortening velocity of the inspiratory muscles, and thus, in PO.…”