Strength Training in Hypoxia to Improve Bone and Cardiovascular Health of Elderly

Participants:

Various associations of pensioners will be contacted as well as the university of seniors of the University of Extremadura to recruit volunteer participants. Total sample size will be 120 people, being this calculated to obtaining a statistical power of 90%, calculated with a margin of error of 5% and a mean difference of 10% in the study variables Design All interventions will be performed during 24 weeks, with a frequency training of 3 days per weeks; sessions will be scheduled with at least one day of rest in between for optimal recovery. All patients were assessed at two time points: at baseline before intervention (Pre) and reassessed 7 days after the last session (Post). Participants will be instructed to continue with their normal daily activities, diet and caloric and calcium intake for the entire duration of the study.

Interventions:

During several times of the session in each intervention, oxygen saturation (SpO2) will be controlled using a finger pulse-oximeter (Konica Minolta, Japan) and heart rate (HR) using a heart rate monitor (Polar team 2, Polar, Finland) to know the physiological challenge posed on the participants during the exposure.

PASSIVE HYPOXIA:

During 30 minutes of session, the participants will be performed an intellectual activity while they will be exposed to normobaric hypoxic conditions in a hypoxic chamber (CAT 310, Lousiville, Colorado). They will inspire oxygen fraction (FiO2) set to 16.1% (0.16) in order to simulate an altitude of 2500m above sea level.

NORMOXIA CIRCUIT TRAINING WITH ELASTIC BANDS Each training sessions will consist of a circuit training, where different muscle groups will be involved (pectoral, shoulders, back, arms, thighs, legs and abdominals). Duration of the session will be about 30 minutes, which will include 10 minutes warm-up consisting of slight movements, and 5 minutes of static stretching for the muscles at the end of the sessions. Main section of the sessions will be a circuit that will be composed by 3 sets of 12-15 repetitions of nine different exercises. Six exercises will be performed using elastic resistance bands (ERS; TheraBand®): chest press, row, glute kickbacks, front and side raises, standing bíceps curls and triceps kickbacks. To provide resistance with ERB, elastic bands with resistance ranging from light to very heavy loading (colors: yellow-gold) were used. ERBs were 2 meters, but the actual length used (grip on ERBs and distance to anchor point) was fine tuned for each subject in each exercise to find the correct resistance. When necessary to increase loading, two or more bands were combined. Bands were prestretched and never elongated more than 300% of resting length, as recommended by the manufacturer. Two additional exercise will be developed with kettlebell (KB): squat with 6 kg or increase loading until 10 kg; and hip trust, increase loading with support of a foot alone or with additional loading (KB of 5 or 10 kg). Finally, the subjects will keep a plank position during 15-20 seconds.

Training will take place in a hypoxia chamber (CAT 310, Lousiville, Colorado, United States) will place in the laboratory. In order to blind subjects to altitude, the system will be run with normoxic airflow into the chamber (up to 1000 l/min) and will produce the same audible noise as in the hypoxic condition. Subjects will inspire FiO2 of 21.0% (0.21) to simulate an altitude of 459 m above sea level. Furthermore, all systems will be covered with fabric to prevent participants from visually identifying the normoxic or hypoxic conditions. FiO2 will be controlled regularly with an electronic device (HANDIC,Maxtec, Salt Lake City, Utah, United States).

HYPOXIA CIRCUIT TRAINING WITH ELASTIC BANDS Each training sessions will consist of a circuit training, where different muscle groups will be involved (pectoral, shoulders, back, arms, thighs, legs and abdominals). Duration of the session will be about 30 minutes, which will include 10 minutes warm-up consisting of slight movements, and 5 minutes of static stretching for the muscles at the end of the sessions. Main section of the sessions will be a circuit, that will be composed by 3 sets of 12-15 repetitions of nine different exercises. Six exercises will be performed using elastic resistance bands (ERS; TheraBand®): chest press, row, glute kickbacks, front and side raises, standing bíceps curls and triceps kickbacks. To provide resistance with ERB, elastic bands with resistance ranging from light to very heavy loading (colors: yellow-gold) were used. ERBs were 2 meters, but the actual length used (grip on ERBs and distance to anchor point) was fine tuned for each subject in each exercise to find the correct resistance. When necessary to increase loading, two or more bands were combined. Bands were prestretched and never elongated more than 300% of resting length, as recommended by the manufacturer. Two additional exercise will be developed with kettlebell (KB): squat with 6 kg or increase loading until 10 kg; and hip trust, increase loading with support of a foot alone or with additional loading (KB of 5 or 10 kg). Finally, the subjects will keep a plank position during 15-20 seconds Training will take place in a hypoxia chamber (CAT 310, Lousiville, Colorado, United States) will place in the laboratory. Participants will inspire a fraction of inspired oxygen (FiO2) of 16.1% (0.16) to simulate an altitude of 2500 m above sea level; FiO2 will be controlled regularly with an electronic device (HANDIC,Maxtec, Salt Lake City, Utah, United States).

NORMOXIA WHOLE-BODY VIBRATION The subjects will perform dynamic and static vibration exercise provide by a commercially available device (Galileo 2000, Novotec GmbH, Pforzheim, Alemania). The duration of the WBV session will be about 30 minutes, which will include 10 minutes warm-up consisting of slight movements, and 5 minutes of static stretching for the muscles at the end of the session.

Repetitions of 30 seconds with a frequency of 18.5 Hz will be performed. The rest interval will be 60 seconds between 4 repetitions during weeks 1-12 and 45 seconds between 5 repetitions during weeks 12-24. The vertical amplitude of WBV was set at 2.5 mm. Four stance will be performance, with the soles of both feet remained in contact with the platform:

• Stand with feet side-by-side on the board, which produced lateral oscillations of the whole body. During the vibration training sessions, the subjects will be barefoot to eliminate any damping of the vibration caused by footwear. The angle of flexion of the knees during the vibration exercise will be set at 60°.
• Begin with the feet placed perpendicular to the midline axis of the platform, with a foot positioned slightly ahead of the other foot. Lift the toes of the one foot and the heel of the other foot 4 mm above the surface of the platform. Bend the knees and maintain a 45°knee angle. Keep the back and head straight. Alternate legs.
• Front foot 4 mm above the surface of the platform and back foot on ground, front knee angle 90°. Alternate legs
• Lay down on the ground, with the knees bent and feet flat on the platform. Keep the arms at your side with your palms down. Lift the hips off the ground until the knees, hips and shoulders form a straight line. Hold your bridged position.

Training will take place in a hypoxia chamber (CAT 310, Lousiville, Colorado, United States) will place in the laboratory. In order to blind subjects to altitude, the system will be run with normoxic airflow into the chamber (up to 1000 l/min) and will produce the same audible noise as in the hypoxic condition. Subjects will inspire FiO2 of 21.0% (0.21) to simulate an altitude of 459 m above sea level. Furthermore, all systems will be covered with fabric to prevent participants from visually identifying the normoxic or hypoxic conditions. FiO2 will be controlled regularly with an electronic device (HANDIC,Maxtec, Salt Lake City, Utah, United States).

HYPOXIA WHOLE-BODY VIBRATION The subjects will perform dynamic and static vibration exercise provide by a commercially available device (Galileo 2000, Novotec GmbH, Pforzheim, Alemania). The duration of the WBV session will be about 30 minutes, which will include 10 minutes warm-up consisting of slight movements, and 5 minutes of static stretching for the muscles at the end of the session.

Repetitions of 30 seconds with a frequency of 18.5 Hz will be performed. The rest interval will be 60 seconds between 4 repetitions during weeks 1-12 and 45 seconds between 5 repetitions during weeks 12-24. The vertical amplitude of WBV was set at 2.5 mm. Four stance will be performance, with the soles of both feet remained in contact with the platform:

• Stand with feet side-by-side on the board, which produced lateral oscillations of the whole body. During the vibration training sessions, the subjects will be barefoot to eliminate any damping of the vibration caused by footwear. The angle of flexion of the knees during the vibration exercise will be set at 60°.
• Begin with the feet placed perpendicular to the midline axis of the platform, with a foot positioned slightly ahead of the other foot. Lift the toes of the one-foot and the heel of the other foot 4 mm above the surface of the platform. Bend the knees and maintain a 45°knee angle. Keep the back and head straight. Alternate legs.
• Front foot 4 mm above the surface of the platform and back foot on ground, front knee angle 90°. Alternate legs
• Lay down on the ground, with the knees bent and feet flat on the platform. Keep the arms at your side with your palms down. Lift the hips off the ground until the knees, hips and shoulders form a straight line. Hold your bridged position.

Training will take place in a hypoxia chamber (CAT 310, Lousiville, Colorado, United States) will place in the laboratory. Participants will inspire a fraction of inspired oxygen (FiO2) of 16.1% (0.16) to simulate an altitude of 2500 m above sea level; FiO2 will be controlled regularly with an electronic device (HANDIC,Maxtec, Salt Lake City, Utah, United States).

Statistical Analysis Statistical analyses will be performed using the statistical analysis package SPSS v.20 (IBM, New York, United States). Data will be expressed as median and standard deviation. Kolmogorov-Smirnov tests will be conducted to show the distribution of the studied variables and Levene's test for homogeneity of variance. Repeated measure ANOVA will be used to compare the response of each variable, considering the sex and age as covariate. The p < 0.05 criterion was used for establishing statistical significance. Effect size (Cohen, 1992) will be also calculated for all variables, considering the magnitude of change as small (0.2), moderate (0.5) or large (0.8).

Inclusion criteria

• women and men aged 65 years or older
• no current medical condition not compatible with planned exercise
• free of illness or medication potentially affecting the bone and cardiovascular system
• estimated daily calcium intake of 1200-2000 mg/day
• consumption of no more than two alcoholic beverages per day.

Exclusion criteria

• participation in any other type of intervention based on physical exercise in the last 6 months in order to avoid interactions with the previous practice
• subjects have been above 1500 m during the last 3 months
• contra indications for whole-body vibration training: severe cardiovascular diseases, ocular diseases that affect the retina, neuromuscular and heart diseases, stroke, implant, bypass, stent, arthritis and other joint disease or epilepsy