Discussion
fatigue, sarcopenia, dementia, acute illness, muscle fatigue
CONTRACTION, SECONDARY, SYNDROMES, SARCOPENIA
The main finding of the present study is that just three sessions of a multicomponent exercise intervention, composed of progressive power training, induced marked increases in muscle power output and maximal strength gains in older patients during acute hospitalization. Additionally, this exercise programme also improved the ability to maintain muscle power output during a set of 10 repetitions of a leg‐press exercise, suggesting a positive benefit on fatigue resistance in these patients. Furthermore, we found moderate associations between maximal strength gains and relative progression in training loading and power output during the exercise programme. Therefore, these findings contribute to our understanding of the positive effects of a multicomponent exercise programme, which minimizes the bed rest hazards associated with acute hospitalization on the neuromuscular function of older individuals.Considering the physical inactivity phenotype, aging is associated with significant losses in maximal strength and power output, which put older individuals at greater risk of functional declines and geriatric syndromes, such as frailty, sarcopenia.Our findings are consistent with those by Sáez de Asteasu et al.,In addition to peak power, we also assessed mean propulsive power to identify different mechanical adaptations following the exercise interventions. We found that all of these muscle function outcomes improved. The increase in mean propulsive power suggests that patients were able to improve power output throughout the entire acceleration phase, indicating an increased velocity during this phase, and explaining the improvement in peak power when considering the same absolute load. These changes are likely associated with concomitant enhancements in rate of force development (RFD), although RFD was not assessed in the present study.Moreover, we observed significant improvements in muscle power output in different load ranges, including light loads (≤30% of 1RM) more associated with functional tasks with lower strength demands (i.e., gait speed), and moderate loads (between 45% and 55% of 1RM), more associated with functional tasks with high strength demands (i.e., sit‐to‐stand ability).We also aimed to investigate the ability to maintain muscle power output during a protocol of ten leg‐press repetitions performed at near to maximal volitional intensity with the % of the 1RM. A new finding of the present study was that the intervention group improved mean peak power during this task, indicating an ability to increase their power output under fatigue conditions and produce more power during a longer task. To our best knowledge, this is the first study investigating the effects of individualized exercise intervention including power training on muscle fatigue in acutely hospitalized older patients. This finding is especially important because an increased fatigue may be one of the possible reasons for prolonged bedridden periods during hospitalization.Another novelty of this study was the monitoring of power progression among the three exercise sessions in the leg press exercise, which allowed us to verify the association between the magnitude of adaptations and different parameters of loading progression. We found moderate associations between maximal strength gains and different training outcomes, such as the progression in the training load, peak power and mean propulsive power, as well as the maximal relative load achieved (i.e., % of 1RM). In addition, we also observed a moderate association between relative gains in the peak power and the progression in the power output among the exercise sessions. While there is a known association between the maximal relative load achieved and the magnitude of maximal strength gains in healthy older individuals,Although functional outcomes were not assessed here, muscle power output consistently associates with functional outcomesOne important consideration is that while tailored multicomponent exercise with power training effectively enhances neuromuscular function, improvements from in‐hospital interventions may not be sustained indefinitely after cessation.The present study has some limitations that should be mentioned. Firstly, this study is based on a secondary exploratory analysis, and the sample size was estimated according to the primary endpoints that are not discussed in this manuscript. Secondly, some patients were unable to complete all the muscle power measurements at admission and discharge, which led to the exclusion of some participants from the power output analysis. The optical encoder used to record muscle power output failed to capture some slow contraction velocities, and this could have affected the results. Finally, these findings pertain specifically to patients with a median hospital stay of 8 days and may not be applicable to patients with longer hospitalizations.However, this study has some potential strengths that need to be highlighted. Firstly, the study was conducted on a very vulnerable population of older patients, including those with dementia and multiple comorbidities, who were hospitalized for acute illness. Secondly, the study focused on various parameters of mechanical muscle function, including different strength and power outcomes, and the power output under fatigue conditions. Lastly, the power output was monitored during the different exercise sessions to verify training progression, which is a critical factor for older individuals during acute hospitalization.In summary, the results of this study indicate that an individualized multicomponent exercise programme that emphasizes progressive power training is an effective intervention for improving muscle power output and maximal strength gains in older patients during acute hospitalization. Furthermore, this exercise program enhances the mean muscle power during a longer protocol, which suggests a positive effect on fatigue resistance in these participants. The maximal strength and peak power gains showed a moderate association with the progression in the loads and power output throughout the program, highlighting the importance of training loading progression during the exercise program in older individuals during acute hospitalization. These findings support the use of multicomponent exercise including power training, as a crucial element to reduce the hazards of prolonged bed‐rest in older individuals, especially concerning muscle function.