Purpose: Investigate neuromuscular, cardiorespiratory, functional capacity, quality of life and cognitive adaptations of eight weeks of water-based aerobic and combined training in elderly women previously trained for eight weeks of water-based aerobic training.

Materials and methods: Fifty-four elderly women volunteer will be randomly divided into two groups with ratio of 2:1 (week 0): water-based aerobic training (WBA) and control group (CG). After eight weeks of intervention the WBA group will be randomly divided into two groups with ratio of 1:1 (week 9): WBA and water-based combined training (WBC). The intervention will last 16 weeks with two weekly sessions for water-based training groups and one weekly session for CG. The WBA program will consist only of aerobic exercises while the WBC program will consist of aerobic and resistance exercises in the same session. The WBA training will be performed in the percentages of heart rate corresponding to the anaerobic threshold and the resistance training sets will be performed at maximal effort. Assessments of muscular endurance of knee extensors and elbow flexors, peak oxygen consumption and ventilatory thresholds, occurrence of low back pain and disability from the same, functional capacity (30-second chair stand, 8-foot up-and-go and chair sit-and-reach) and of functional test 8-foot up-and-go with counting task will be performed before (week 0) and after interventions (week 17). Moreover, assessments of maximal dynamic strength in knee extensors and elbow flexors, maximal neuromuscular activity and maximal voluntary isometric contraction of knee extensor muscles, muscle thickness and echo intensity of knee extensor muscles, heart rate, blood pressure, functional capacity (6-minute walk), quality of life and cognitive function will be performed before (week 0), between (week 9) and after interventions (week 17). The data will be analyzed using Generalized Estimating Equations (GEE) and Bonferroni post-hoc test (α=0,05).

Aging process has its own characteristics, among which the direct association with reductions in muscle mass, muscle strength and cardiorespiratory fitness are highlighted. These reductions cause impairment in functional capacity, affecting the efficiency of elderly individuals to perform daily living tasks. However regular exercise practice can be efficient to mitigate factors associated with aging.

A modality that has been well suited for individuals over 60 years is the water-based exercises training, precisely due to the beneficial conditions of the aquatic environment, such as the lower impact on the lower limbs joints in comparison to the impact observed during exercises performed on land

The aim of the study is to investigate neuromuscular, cardiorespiratory, functional capacity, quality of life and cognitive adaptations of eight weeks of water-based aerobic and combined training in elderly women previously trained for eight weeks of water-based aerobic training.

Volunteer old women age range: 60-75 years old, will participate to this study, and will randomly divided into three groups: water-based aerobic training group (WBA), water-based aerobic and combined training group (WBAC) and control group (CG).

Fifty-four elderly women volunteer will be randomly divided into two groups with ratio of 2:1 (week 0): WBA and CG. After eight weeks of intervention the WBA group will be randomly divided into two groups with ratio of 1:1 (week 9): WBA and water-based combined training (WBC).

The intervention will last 16 weeks with two weekly sessions for water-based training groups and one weekly session for CG. The WBA program will consist only of aerobic exercises while the WBC program will consist of aerobic and resistance exercises in the same session.

Participants who will be randomized for WBA group will carry out exercises with no interval for exercise change. Intensity will be increased every mesocycle. In the first mesocycle (weeks 1-2), participants will carry out three 3-minute series of each exercise whose intensity corresponds 80-85% of heart rate corresponding to the anaerobic threshold (HRat). In the second mesocycle (weeks 3-4), participants will perform three 3-minute series of each exercise corresponding to 85-90% of HRat. In the third mesocycle, participants will perform three 3-minute series of each exercise at intensity corresponding to 90-95% of HRat from weeks 5-7. In the fourth mesocycle, participants will perform three 3-minute series of each exercise at intensity corresponding to 95-100% of HRat from weeks 8-10. In the fifth mesocycle (weeks 11-13) comprises three 3-minute series of each exercise whose intensity corresponds to the 100-105% of HRat for 2 minutes and <85% of HRat for 1 minute. The last mesocycle (weeks 14-16) comprises three 3-minute series of each exercise whose intensity corresponds to the 105-110% of HRat for 2 minutes and <85% of HRat for 1 minute.

Resistance training will be divide into two blocks of exercises, and each block will be compose of one exercise for the upper and one for the lower limbs. Block 1 will consist of shoulder flexion and extension (bilateral) and hip flexion and extension (unilateral) exercises. Block 2 will consist of elbow flexion and extension (bilateral) and knee flexion and extension, starting from 90° of hip flexion (unilateral), exercises. In the first mesocycle (weeks 9-10) participants will perform 2 sets of 30 s for each block with the following sequence: 30 s of exercise for the lower limb (right leg), 5 s for switching, 30 s of exercise for the lower limb (left leg), 5 s for switching and 30 s of exercise for the upper limbs. The blocks sequences and intervals will be as follows: block 1 (4 min 20s), interval between blocks (1 min) and block 2 (4 min 20 s). In the second mesocycle (weeks 11-13) participants will perform 3 sets of 20 s for each block.The blocks sequences and intervals will be as follows: 3 times block 1 (6 min 10 s), interval between blocks (1 min) and block 2 (6 min 10 s). In the third mesocycle (weeks 14-16) the participants will perform 4 sets of 15 s for each block. The blocks sequences and intervals will be as follows: 4 times block 1 (8 min 10 s), interval between blocks (1 min) and 4 times block 2 (8 min 10 s).

Assessments of muscular endurance of knee extensors and elbow flexors, peak oxygen consumption and ventilatory thresholds, occurrence of low back pain and disability from the same, functional capacity (30-second chair stand, 8-foot up-and-go and chair sit-and-reach) and of functional test 8-foot up-and-go with counting task will be performed before (week 0) and after interventions (week 17). Moreover, assessments of maximal dynamic strength in knee extensors and elbow flexors, maximal neuromuscular activity and maximal voluntary isometric contraction of knee extensor muscles, muscle thickness and echo intensity of knee extensor muscles, heart rate, blood pressure, functional capacity (6-minute walk), quality of life and cognitive function will be performed before (week 0), between (week 9) and after interventions (week 17).

The data will be analyzed using Generalized Estimating Equations (GEE) and Bonferroni post-hoc test (α=0,05).

Inclusion Criteria:

• Volunteer elderly women, aged between 60-75 years old who were not participating on any regular training program in the last four months

Exclusion Criteria:

• Cardiovascular disease (except hypertension controlled by medication);
• Physical impairments for exercise diagnosed through anamnesis;