The aim of the study is to investigate the effects of two water based aerobic training programs on cardiorespiratory, neuromuscular and quality of life parameters in old women.

Volunteer old women age range: 60-75 years old, will participate to this study, and will randomly divided into two groups: continuous aerobic training group and interval aerobic training group.

Both group subjects will participate in two-week training sessions during 12 weeks. Independent of the group, participants will perform three water-based exercises: stationary running, frontal kick and cross-country skiing. The intensity of aerobic exercise will be based Rating Perceived Exertion (RPE). Along the training, the intensity of aerobic exercise will increase in both groups. Before and after intervention, there will be evaluation of muscle quality, muscle thickness, peak oxygen uptake and oxygen uptake at ventilatory threshold, maximal isometric and dynamic strength of knee extensors, maximal and submaximal isometric eletromiografy (EMG) activity of vastus lateralis and rectus femoris, muscle endurance, performance in functional tests and assessment of the perception of quality of life.

Data will be analyzed by Generalized Estimating Equations (GEE) and Bonferroni's post-hoc test (α=0.05), including both protocol and intention to treat analyses (α=0,05).

Aging is associated with impairment in cardiorespiratory fitness, strength performance and muscle mass decrease, which affects the functional capacity of older adults directly. Consequently carrying out routine activities can be harmed. However regular exercise practice points out as an efficient tool to mitigate factors associated with aging.

Therefore, carrying out water-based exercises has been widely suggested for older adults due to their advantages, such as low impact on lower limbs and lower cardiovascular load.

The aim of the study is to investigate the effects of two water based aerobic training programs on cardiorespiratory, neuromuscular and quality of life parameters in old women.

Volunteer old women age range: 60-75 years old, will participate to this study, and will randomly divided into two groups: continuous aerobic training group and interval aerobic training group.

Both group subjects will participate in two-week training sessions during 12 weeks. Independent of the group, participants will perform three water-based exercises: stationary running, frontal kick and cross-country skiing. The intensity of aerobic exerecise will be based Rating Perceived Exertion (RPE). Along the training, the intensity of aerobic exercise will increase.

Participants who will be randomized for the continuous aerobic training group will carry out exercises with no interval for exercise change. Intensity will be increased every mesocycle. In the first mesocycle (weeks 1-4), participants will carry out three 4-minute series of each exercise whose intensity corresponds to the Rating of Perceived Exertion (RPE) 13. In the second mesocycle (weeks 5-8), participants will perform four 3-minute series of each exercise corresponding to RPE 14. In the third mesocycle, participants will perform six 2-minute series of each exercise at intensity corresponding to RPE 15 from weeks 9-10, whereas intensity corresponding to RPE 16 will be experienced from weeks 11-12.

Participants who will be randomized for interval aerobic training group will carry out exercises which associate effort phases, at higher intensity and recovery phases, at lower intensity, with no interval for exercise change. Intensity will be increased every mesocycle. The first mesocycle (weeks 1-4) comprises three 4-minute series of each exercise whose intensity corresponds to the RPE 16 for 2 minutes and RPE 11 for 2 minutes. The second mesocycle (weeks 5-8) includes four 3-minute series of each exercise whose intensity corresponds to the RPE 17 for 1.5 minutes and RPE 11 for 2 minutes. The third mesocycle (weeks 9-12) comprises six 2-minute series of each exercise whose intensity corresponds to the RPE 18 for 1 minute and RPE 11 for 1 minute.

Before and after intervention, there will be evaluation of muscle quality, muscle thickness, peak oxygen uptake and oxygen uptake at ventilatory threshold, maximal isometric and dynamic strength of knee extensors, maximal and submaximal isometric eletromiografy (EMG) activity of vastus lateralis and rectus femoris, muscle endurance, performance in functional tests and assessment of the perception of quality of life.

Data will be analyzed by Generalized Estimating Equations (GEE) and Bonferroni's post-hoc test (α=0.05), including both protocol and intention to treat analyses (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 six months.

Exclusion Criteria:

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