Effects of Traditional strength training and resistance training applied by a partner, with or without feedback, on muscle mass loss and fear of falling in older adults

INTERVENTION: This is a randomized, controlled clinical trial with four parallel arms and a test‐intervention‐retest design. The sample will consist of 80 individuals of both sexes, aged 60 years or older, with 20 participants allocated to each group. Participants will be randomly allocated, at a 1:1:1:1 ratio, to four parallel groups through a randomization process conducted by a researcher who will not participate in the assessments or intervention procedures: 1) traditional machine‐based resistance training, 2) manual resistance training without feedback, 3) manual resistance training with feedback, and 4) Active Control group. The assessors responsible for the pre‐ and post‐intervention assessments will be blinded to participants’ group allocation, thereby ensuring assessor blinding. Due to the nature of the interventions, participants and researchers responsible for delivering the training cannot be blinded to group allocation. The intervention will consist of resistance training programs performed three times per week, on non‐consecutive days, for 12 weeks, totaling 36 training sessions, with each session consisting of 8 exercises for both the upper and lower limbs, including leg extension, leg curl, Scott curl, triceps exercise, and reverse fly. The three resistance training groups will perform the same exercises with progressive training volume, ranging from 3 to 5 sets of 6 repetitions throughout the 12 weeks, with 180‐second rest intervals between sets and a duration of 6 seconds per repetition, consisting of 3 seconds for the concentric action and 3 seconds for the eccentric action. Training intensity for each group will be controlled as follows: in the traditional machine‐based resistance training group, intensity will be set at 60% of the performance achieved in the one‐repetition maximum test; in the manual resistance training group without feedback, intensity will be based on the Rating of Perceived Exertion, maintained between 13 and 15 points on the Borg scale; and in the manual resistance training group with feedback, resistance will be applied by a researcher using a portable force sensor, aiming to achieve a value corresponding to 60% of the value achieved in the Maximum Voluntary Isometric Contraction test. The Active Control group will consist of individuals who regularly participate in physical activities or physical activity programs designed for older adults. During the 12‐week study period, these participants will be instructed to maintain their usual physical activities without participating in the specific resistance training programs proposed for the other groups. Thus, participants in the Active Control group will maintain their usual physical activity routine throughout the intervention period and will undergo the study assessments at the same time points as the other groups. Assessments will be conducted before the beginning of the intervention and after the 12‐week intervention period, including panoramic ultrasonography to determine muscle cross‐sectional area, electromyography to assess muscle co‐contraction, tests related CONDITION: Aged ; Sarcopenia C10.597.613.612.500 INCLUSION CRITERIA: Age = 60 years; male or female sex; ability to walk independently without assistance; absence of visual impairments or use of visual corrective devices; Mini‐Mental State Examination (MMSE) score = 27. PRIMARY OUTCOME: An increase in the maximal strength performance of the older participants is expected after twelve weeks of resistance training. This outcome will be assessed using the Maximum Voluntary Isometric Contraction test, performed at the midpoint of the range of motion on properly instrumented equipment. Peak force values, measured in Newtons, achieved during knee flexion and extension, hip extension, elbow flexion and extension, and horizontal shoulder abduction will be recorded The effect on fear of falling in a situation involving a threat of falling after twelve weeks of intervention will be assessed. This outcome will be evaluated through completion of the Activities‐specific Balance Confidence Scale questionnaire and performance of a motor task on a platform elevated 0.6 meters above the ground to elicit fear of falling. The total questionnaire score, degree of conscious control, self‐reported state anxiety, and muscle co‐contraction indices between the soleus and tibialis anterior muscles obtained through electromyography will be assessed The effect on muscle cross‐sectional area in the upper and lower limbs after twelve weeks of intervention will be assessed. This outcome will be evaluated using panoramic ultrasonography, with measurements of the cross‐sectional area, expressed in square centimeters, of the rectus femoris, vastus lateralis, biceps femoris, biceps brachii, triceps brachii, and latissimus dorsi muscles; SECONDARY OUTCOME: Outcome 10: The effect on psychosocial responses, specifically self‐reported state anxiety, after twelve weeks of intervention will be assessed. This outcome will be evaluated through a motor task consisting of walking on a platform elevated 0.6 meters above the ground to elicit fear of falling. Self‐reported state anxiety scores obtained in response to the fall‐threat manipulation will be assessed Outcome 11: The reliability of data recording and the accuracy of the loads applied during manual resistance training compared with traditional machine‐based resistance training after twelve weeks of intervention will be assessed. This outcome will be evaluated through the instrumentation of equipment with sensors and the use of a portable handheld device integrated with an application providing real‐time feedback. The magnitude of the resistance force, measured in Newtons, and the similarity of the recorded values between the training groups will be assessed, aiming to ensure standardization, secure data storage, and effective control of training intensity throughout the intervention. Outcome 4: The effect of the intervention on heart rate will be assessed. This outcome will be evaluated by measuring heart rate using a heart rate monitor, with the heart rate values achieved, expressed in beats per minute, being recorded Outcome 5: The effect of the intervention on blood pressure will be assessed. This outcome will be evaluated by measuring blood pressure using a sphygmomanometer, with systolic blood pressure and diastolic blood pressure values, expressed in millimeters of mercury, being recorded Outcome 6: The effect of the intervention on heart rate variability in response to resistance exercise will be assessed. This outcome will be evaluated by measuring the intervals between heartbeats using a heart rate monitor, with the indices derived from heart rate variability analysis being assessed. The data will be collected and processed using specialized software to ensure the accuracy of the recorded autonomic parameters Outcome 7: The effect of the intervention on ambulatory blood pressure monitoring will be assessed. This outcome will be evaluated using a portable automatic blood pressure monitor for ambulatory recording, with systolic blood pressure and diastolic blood pressure values, expressed in millimeters of mercury, recorded over a 24‐hour period. The biological data will be collected and processed using specialized software by researchers who have previously undergone training in biological data processing Outcome 8: The effect on electromyographic activity and the pattern of muscle co‐contraction after twelve weeks of intervention will be assessed. This outcome will be evaluated using surface electromyography, in which all biological data will be collected and processed using specialized software to ensure technical rigor and methodological reproducibility. The signals will be processed by researchers who have previously undergone personnel training in biological data processing. The amplitude of the muscle electrical signal, measured in microvolts and millivolts, and the co‐contraction indices between the soleus and tibialis anterior muscles will be assessed. The co‐contraction values will be normalized by the Root Mean Square obtained during the Maximum Voluntary Isometric Contraction test and will be determined during balance and walking tasks on the elevated platform to assess fall risk Outcome 9: The effect on balance and confidence in performing daily activities after twelve weeks of intervention will be assessed. This outcome will be evaluated through completion of the Activities‐specific Balance Confidence Scale questionnaire, considering the total score obtained on the questionnaire