Tai Chi Chuan Combined With Walking on Physical and Mental Parameters of Older Adults

The same knee extension machine is used to assess dynamic muscular endurance. To do so, participants perform the maximal number of bilateral knee extension repetitions at 60% of their 1RM. The test cadence (2 s for each contraction phase) and range of motion are the same for the 1RM test. The post-intervention assessment is performed using the same absolute load employed at baseline (i.e., 60% of baseline 1RM).

The Handgrip isometric strength will be accessed using a handgrip dynamometer (Jamar, Sammons Preston Inc.®). Participants must be seated and with the elbow of the limb to be evaluated flexed at 90° without any external support. Both hands will be measured. On command, participants must squeeze the dynamometer as hard as possible for 5 seconds. Three attempts will be made for each hand, with a 1-minute interval between attempts, and the highest value achieved will be recorded, which is measured in Kilogram-Force (kgf).

The isometric back-leg-chest strength will be accessed using the back-leg-chest dynamometer (Crown, Oswaldo Filizola Ltda.), as illustrated in Figure 19. Participants must position themselves on the equipment platform with their knees extended, hips flexed at approximately 60 degrees, hands holding the equipment bar, and look straight ahead. On command, participants must pull the dynamometer upwards, exerting as much force as possible. Three attempts will be made with a 1-minute interval between attempts, and the highest value achieved will be recorded, which is measured in Kilogram-Force (kg).

The Arm Curl test is performed to measure the strength of the upper limbs. Starting at full elbow extension and holding a 2 kg dumbbell in each hand, participants are instructed to perform the maximal number of elbow crunches over the full range of motion for 30 s. The test is performed with both upper limbs.

The 8-ft Up-and-Go test is performed to measure agility and dynamic balance. Participants are instructed to get up from the chair (43 cm), turn around a marker that will be 2.44m, and return to the starting position. The shortest time of two attempts will be considered as a result.

The Chair Sit-and-Reach test is performed to measure the flexibility of the lower limbs. Participants sit on the front edge of a chair and extend one leg straight out in front of the hip, with foot flexed and heel resting on the floor (the other leg is bent, foot flat on the floor). The object is to reach as far forward as possible toward (or past) the toes. The investigator uses a ruler noting the cm left to reach the toe (negative score) or the cm that went past the toe (positive score).

The Back Scratch test is performed to measure the flexibility of the upper limbs. Participants are instructed to try to touch the middle fingers of both hands together behind the back. The investigator uses a ruler noting the cm left to reach the middle fingers (negative score) or the cm that the middle fingers overlapped (positive score).

The 6-min Walk test is performed to measure aerobic fitness. The course proposed in the original test is 45.72 m rectangular. The course will be adapted for a straight line with 30 m length, demarcated with cones every 3 m. Participants are instructed to walk for 6-min in a flat 30m course, in which the total distance walked "as fast as possible" is assessed.

The static balance will be determined through the 30-second single-leg stance test (Briggs et al., 1989). The subjects will be positioned facing the wall, at a distance at which they can rest their hands on the wall at shoulder height with their elbows extended. They will be asked to choose one of their lower limbs, whichever they feel most comfortable balancing on. At the signal, they will be asked to look at a fixed point on the wall, lower their upper limbs, keeping them glued to the body in an orthostatic position, and flex the knee of the lower limb not chosen to approximately 90 degrees, remaining in single-leg support. Three attempts will be made, and the longest time (30 s maximum) that participants are able to maintain a single-leg balance will be recorded.

Transversal images of the four portions of the quadriceps femoris are obtained by B-mode ultrasonography with a 7.5 megahertz linear array probe. Images of the vastus lateralis (VL), rectus femoris (RF), and vastus intermedius (VI) muscles are obtained at the midpoint between the anterosuperior iliac spine and the upper edge of the patella, whereas the vastus medialis (VM) is assessed at 30% of the distance between the lateral condyle and the greater trochanter of the femur. All images will be analyzed using the ImageJ software (National Institutes of Health, USA, version 1.37). The muscle thickness will be assessed as the distance from each muscle's superior and inferior muscle aponeurosis. Overall quadriceps femoris muscle thickness will be calculated as the sum of each muscle thickness (i.e., RF + VL + VM + VI).

Transversal images of the four portions of the quadriceps femoris are obtained by B-mode ultrasonography with a 7.5 megahertz linear array probe. Images of the VL, RF, and VI muscles are obtained at the midpoint between the anterosuperior iliac spine and the upper edge of the patella, whereas the VM is assessed at 30% of the distance between the lateral condyle and the greater trochanter of the femur. All images will be analyzed using the ImageJ software. Muscle quality will be determined by the echo intensity values, which will be calculated from gray-scale analysis using the standard histogram function in ImageJ. The echo intensity of the quadriceps femoris will be calculated as the mean of echo intensity values of the four individual quadriceps femoris muscles ((RF + VL + VM + VI)/4).

Aspects of objective cognitive function are measured by the Trail Making Test (TMT). The version validated for the Brazilian population of TMT (Carvalho \& Caramelli, 2020) is used to assess domains such as attention, motor skills, processing speed and cognitive flexibility (Bowie \& Harvey, 2006). In the first part of the instrument (TMT-A), participants will have to draw a line connecting the numbers from 1 to 25 in ascending order. Then, letters (A-L) will be added so that the participants trace a line again following a numerical (1-13) and alphabetical order, interleaved (TMT-B). Participants will be instructed to maintain pencil-to-paper contact during the test. A shorter runtime indicates better performance.

Aspects of objective cognitive function are also measured by the Controlled Oral Word Association Test (COWAT). The COWAT is used to assess verbal fluency, working memory and inhibitory control (Ross et al., 2007). In this test the participants will have to speak as many words as possible that start with the letters "F", "A" and "S", within 1 minute for each letter. Proper names, repeated words and variations in gender, number and conjugation will not be considered. The greater number of words evoked in each test indicates better verbal fluency.

Quality of life will be measured using the Abbreviated World Health Organization Quality of Life (WHOQOL-Bref) questionnaire, a validated version in Brazilian Portuguese (Fleck et al., 2000). The questionnaire has 26 questions, two general questions about quality of life, and 24 divided into four domains with six questions each: physical, psychological, social relationships, and environment.

The participants' perceived sleep quality will be measured using the Pittsburgh Sleep Quality Index, a validated version in Brazilian Portuguese (Passos et al., 2017). The questionnaire has 19 self-rated questions and five questions rated by the bed partner or roommate (if any) that investigate the quality and possible sleep disturbances during the last month across seven domains: subjective quality, sleep latency, sleep duration, sleep efficiency, sleep disorders, medication use, and daily dysfunction. Each domain has a score that varies from 0 to 3 points, totaling a maximum of 21 points. Scores above 5 points indicate poor sleep quality. The questions evaluated by the partner/colleague are not considered when calculating the final score and, for logistical reasons, will be removed from the data collection instrument.

HADS was developed by Zigmond and Snaith (1983), with translation and validation for the Brazilian population (Botega et al., 1995). It is an instrument composed of 14 items, seven of which form the anxiety subscale and the other seven the depression subscale, allowing the assessment of symptoms in the previous week. Each HADS item has four response options ranging from 0 to 3, reaching a maximum of 21 points in each subscale.