This study was a randomized controlled clinical trial involving older adults. Participants were assigned either to training using a remotely supervised exercise App (Experimental Group - EG) or to training using an exercise App under face-to-face supervision (Control Group - CG). Functional capacity (primary outcome), postural balance, lower-limb strength, satisfaction, motivation, and attendance (secondary outcomes) were obtained at baseline, after 4 weeks, and after 8 weeks of intervention.

Fifty older adults residing in São Paulo, Brazil, were recruited. Inclusion criteria required participants to be between 60 and 80 years old (with an upper age limit to ensure sample homogeneity), physically active, and functionally independent with a Katz^{( 20 )} score ≥4. Participants also had to be vaccinated against coronavirus disease (COVID-19), exhibit preserved cognitive function (assessed using the Mini-Mental State Examination,^{( 21 )}) and have no neurological, cardiovascular, or musculoskeletal diseases contraindicating physical exercise. All participants provided written informed consent.

All assessments were conducted in the Rehabilitation Sciences laboratory of the Master’s and Doctoral programs at Universidade Nove de Julho , São Paulo, Brazil. Participants in the Experimental Group performed the exercises in the laboratory, and Control Group participants performed the exercises at home.

Participants were randomized to the Control Group (CG), which performed the App-based exercises in the laboratory during individual sessions supervised by a therapist, or to the Experimental Group (EG), which completed App-based exercises at home. The EG could contact the therapist via phone or message for clarification or guidance if they had difficulties performing the exercises. Furthermore, therapists frequently contacted patients to identify any complications.

The exercise program was conducted using the free application ‘Exercise for Older Adults’ available for Android and iOS platforms. All patients were familiar with smartphones. The researcher installed the application on the participants’ smartphones and instructed them to use it before performing the activities.

The training program used the ‘Improve your strength and balance’ exercise category, which included warm-up exercises, stationary running, free movement and small jumping tasks, and lower limb strength exercises (such as sit-to-stand, squats and lunges) abdominal exercises and bi- and single-leg balance exercises; Table 1S , Supplementary Material). The EG received a booklet explaining how to perform each exercise, based on the application manual.

Table 1S

Instructions:
1) You are receiving a booklet with guidelines for exercises that will be performed using the application.
2) The exercise program should conducted 3 days a week.
3) Before performing exercises, measure your blood pressure with the pressure measuring device and ensure you are feeling comfortable, without shortness of breath or anxiety.
4) Make sure you are wearing comfortable clothing, not too tight:
T-shirt (tank top, cotton, nylon);
Pants (sweatshirt, nylon pants, or leggings; avoid jeans);
Footwear (sneakers or closed shoes that do not slip)
5) Prepare the exercise area
Do not leave many objects nearby, except for the chair and supports;
Use a firm, heavy chair to prevent it from tipping over or moving out of place during exercises.
6) Exercises
Abdominal exercises are performed on a mat. If you don’t have one, it can be done lying down in your bed;
The exercises are performed standing close to a wall.
Walking exercises should preferably be performed in a hallway or near a wall to support yourself if you lose your balance.
All exercises are timed and must be performed with the application installed on your smartphone/cell phone.
Always rest after each exercise.
Run in place Perform movements as if you were running but without leaving the place (do it for 1 minute)
Boxing movements Perform movements as if you are throwing punches (perform for 1 minute).
Walk by raising your leg high, bending your knee and hip (perform for 1 minute)
Single limb stance Stand behind a chair or fixed surface, support yourself with one hand. Lift your right foot off the floor and try to balance on your left leg. Try to maintain this position for as long as the exercise lasts. Repeat the same exercise on the other side. The objective of this exercise is to try to stand on one foot without holding onto the chair, maintaining this position for as long as possible.
Walking heel to toe You will walk in a straight line positioning your right foot in front of your left foot, such that your right heel touches the tip of your left foot’s toes. Move your left foot in front of your right, touching your heel to the toes of your right foot. Repeat this movement during the exercise time.
Chair squat Stand with your feet hip-width apart and in front of a chair. Keeping your chest straight and looking straight ahead as you slowly lean your butt back, bending your knees and slowly sitting up. Touch your butt to the chair or sit on it. Tilt your torso slightly forward to stand up. Stand up slowly until reaching an upright posture. Repeat this movement for as long as the exercise lasts. Be careful not to fall during the movements.
Lunges Stand with your feet hip-width apart. Contract your abdomen. Take a big step forward with your right leg. Slowly start to squat, trying to bring your knee close to the floor. Be careful not to hit your knee hard on the floor. Always keep your torso straight. Avoid placing the knee of the right leg too far in front of the right foot. Return to the starting position and repeat the same movement on the other side.
Rock the boat Stand with your feet hip-width apart. Make sure both feet are firmly placed on the floor. Keep your head up looking straight ahead. Shift your body weight onto your right foot and slowly lift your left leg off the floor. Try to maintain this position for as long as the exercise lasts. Repeat the same movement on the other side, slowly lifting the opposite leg.
Clock reach You will need a chair for this exercise. Imagine that you are in the center of a clock. Number 12 is right in front of you and number 6 is right behind you. Hold the chair with your left hand. Raise your right leg and stretch your right arm pointing forward. Point your arm to the side, then behind you. Bring the arm back to the side, then forward. Keep your head straight and looking forward at all times. Repeat this exercise on both sides.
Bicycle crunches Lie on the floor or bed, face up. Place your hands behind your head and try to pedal while keeping your abdomen contracted throughout the movement. As you bend your knee, try to bring your opposite elbow toward it, until it touches your knee. Ensure your rib cage is moving (rotating) with your elbow movements.
Back leg raise Stand behind a chair. Slowly lift your right leg back without bending your knees or stretching your toes. Hold this position for a second, then gently lower your leg. Repeat the movements alternating feet with each left and right leg.
Single limb stance with arms Stand with your feet together and arms at your sides next to the chair. Raise your left hand over your head and slowly lift your left foot off the floor. Hold this position for 10 seconds. Repeat the same action on the right side.
Side leg rise You will need a chair for this exercise. Stand behind the chair with your feet slightly apart. Slowly lift your right leg out to the side. Keep your back straight, your big toe pointed forward and look straight ahead. Lower your right leg slowly. Repeat this movement alternating feet.

Participants were required to perform the exercises three times a week for 8 consecutive weeks, totaling 24 sessions. Each session lasted approximately 45 min, with duration varying according to the rest interval between each exercise. Participants selected their preferred rest interval time, which could vary between 30 and 60 s.

As a protective measure, the therapist assessed the CG participants’ blood pressure and heart rate before and after exercise using an automatic sphygmomanometer.

The EG was instructed to have these measurements taken before and after each exercise session, subsequently reporting the values to the researcher.

To characterize the sample, demographic data collected including age, weight, height, and body mass index (BMI) was collected using a questionnaire. Symptoms of depression and sleep-related disorders were assessed using the Beck Depression Inventory^{( 22 )} and the Pittsburgh Sleep Quality Index,^{( 23 )} respectively, to characterize the sample.

Primary and secondary outcomes were measured pre- and post-intervention

Functional capacity was assessed using the Glittre Activities of Daily Living (ADL) test, previously validated for older adults by Gomes et al.^{( 24 )} The test began when participants rose from a chair (without upper limb support, 46cm from feet to seat), while wearing a backpack (2.5kg for women or 5.0kg for men). Participants subsequently walked 10m on a flat track and halfway up and down two steps (step measurements 17cm high ×27cm deep) and continued walking towards a shelf where there were three objects weighing 1kg. Each weight was transferred, one at a time, with both hands, from the upper shelf (at the height of the participant’s shoulders) to the lower shelf (at the level of the participant’s pelvic girdle) and from there to the floor. Thereafter, participants placed the objects again on the central shelf and then on the top shelf, returned along the 10-meter route, went up and down the steps, and sat back on the chair ( Figure 1 ).

Figure 1 Own Source

This circuit was repeated five times, as quickly as possible, without running. The shorter the time (s) to perform the test, the better the individual’s functional capacity. The predicted time (s) of the Glittre-ADL test was calculated for adult participants based on age, BMI, and height as independent variables, as described by Reis et al.,^{( 25 )} using the Glittre test formula: predicted ADL=0.558 + (0.018 × BMI) + (0.016 × age years).

Postural balance was measured using the Mini-Balance Evaluation System Test,^{( 26 )} assessing balance during anticipatory postural adjustments, postural responses, sensory orientation, and gait. The score varied from 0 to 28 points; the higher the score, the better the balance.

Lower limb strength was evaluated with the Five Times Sit-to-Stand test.^{( 27 )} This measures the time it takes the individual (s) to rise from a chair with a backrest and no armrests to a standing position, repeating the movement five times.

Participant satisfaction and motivation with the exercise program were assessed using a researcher-developed questionnaire. The questionnaire contained the following questions: Were you satisfied with the exercise App? (Yes or no, and then rate from zero to 10). Were you satisfied with the exercise program? (Yes or no, and then rate from zero to 10). How motivated are you with the exercise program? (Not motivated, slightly motivated, moderately motivated, very motivated, and extremely motivated).

The sample size was based on a pilot study with ten participants, five participants per group. Using an effect size of 0.55, an α=0.05, and β=0.8, the estimated required sample size was 28 participants. However, owing to dropout risk, an additional 20% of the sample was included, resulting in a total sample of 34 participants.

An independent researcher randomized the participants into the EG and CG using block randomization via www.randomizer.org. A blinded researcher, unaware of each participant’s exercise program allocation, conducted assessments.

Data normality was assessed using the Shapiro-Wilk test. Continuous data were expressed as the mean±standard deviation, and categorical data as absolute and relative frequencies. Baseline group comparisons were performed using the Independent t-test and Fisher’s exact test. The effects of exercise training programs were analyzed using the Generalized Estimation Equation. Eta squared (η² ) was presented as a measure of effect size. For inferential analysis, statistical significance was set at p<0.05.