Respiratory training as strategy to prevent cognitive decline in aging: a randomized controlled trial

Abstract

Background

Inadequate oxygenation may cause lesions and brain atrophy during aging. Studies show a positive association between pulmonary function and the cognitive performance of individuals from middle age on.

Objective

To investigate the effect of aerobic physical exercises and respiratory training on the blood oxygenation, pulmonary functions, and cognition of the elderly.

Design

This was a randomized and controlled trial with three parallel groups. A total of 195 community-dwelling elderly were assessed for eligibility; only n=102 were included and allocated into the three groups, but after 6 months, n=68 were analyzed in the final sample. Participants were randomized into a social interaction group (the control group), an aerobic exercise group (the “walking” group), or a respiratory training group (the “breathing” group). The main outcome measures were the Wechsler Adult Intelligence Scale, Wechsler Memory Scale, Wisconsin Card Sorting Test, respiratory muscular strength, cirtometry (thoracic–abdominal circumference); oxygen saturation in arterial blood (SpO₂), and hemogram.

Results

No differences were observed for any of the blood parameters. Aerobic exercise and respiratory training were effective in improving the pulmonary parameters. Better cognitive performance was observed for the breathing group as regards abstraction and mental flexibility. The walking group remained stable in the cognitive performance of most of the tests, except attention. The control group presented worst performance in mental manipulation of information, abstraction, mental flexibility, and attention.

Conclusion

Our results showed that both the walking and breathing groups presented improvement of pulmonary function. However, only the breathing group showed improved cognitive function (abstraction, mental flexibility). The improvement in cognitive functions cannot be explained by blood parameters, such as SpO₂, erythrocytes, hemoglobin, and hematocrit.

Keywords:

• breathing exercises
• cognition
• exercise

Acknowledgments

We thank the following agencies and institutions for their funding of our research: National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq/Brasil), São Paulo Research Foundation (Fundação de Amparo à Pesquisa do Estado de São Paulo), and Research Incentive Fund Association (Associação Fundo de Incentivo à Pesquisa).

Disclosure

The funding agencies had no role in study design, data collection, analysis and interpretation of data, writing of the report, or the decision to submit the report for publication. The authors report no conflicts of interest in this work.

Supplementary materials

Details of the interventions

Aerobic exercise group (the “walking” group)

The maximal heart rate (HR_max) was estimated with the equation:

${\mathrm{HR}}_{\max }=220-\text{age}$(1)

the heart rate reserve (HRR) was calculated from the heart rate at rest (HR_rest), using the equation:

$\mathrm{HRR}={\mathrm{HR}}_{\max }-{\mathrm{HR}}_{\mathrm{rest}}$(2)

The training intensity was calculated with the equation:

$\text{Intensity}=\%\text{of target intensity}({\mathrm{HR}}_{\max }-{\mathrm{HR}}_{\mathrm{rest}})+{\mathrm{HR}}_{\mathrm{rest}}$(3)

The intensity was adjusted at the beginning of each month, and the volunteers followed the following training schedule: 2 months at their own chosen of intensity (adaptation), 2 months at 60%–70% of HRR, and 2 months at 70%–80% HRR. The program was performed in two public parks. The parks are safe, clean, well-wooded, and have appropriate space to practice physical exercises.

Respiratory training group (the “breathing” group)

The breathing exercises were performed sitting in a comfortable upright position with spine straight. For each session, seven exercises were chosen from the list below.

1. “Low” breathing (abdominal or diaphragm breathing): While sitting, maximum inspiration was taken through the nose, while relaxing the abdomen; after, maximal inspiration was taken while contracting the abdomen.

2. “High” breathing (“clavicular breathing”): While sitting, the abdomen was kept contracted; in this position, a breath was taken through the nose, filling and emptying the chest only (The breathing in this position is difficult and short).

3. “Middle” breathing: While sitting, the abdomen was lightly constricted, and then, a breath was taken through the nose mainly, with expanding of the middle region of the trunk (position of eighth to 12th ribs); after, the breath was slowly released.

4. “Alternate” breathing: While sitting, inhalation was done through both nostrils, with exhalation through the left nostril and right nostril, alternately. Blockage of the nostrils on the exhale was done alternately with the index finger and thumb of the hand of preference.

5. “Bellows” breathing: While sitting, with mouth gently closed, breathing in and out of the nose was done as fast as possible. This exercise could be performed with low, middle, or high breathing.

6. “Hara” breathing: While sitting, slow inspiration was done through the nose followed by a pause; then the breath was exhaled with the mouth open (pronouncing “fffff…”). The abdomen remained relaxed and returned to starting position to the end of expiration.

7. “Yawn” breathing: While sitting, a maximal inspiration was followed by expiration with mouth open, with the pronouncement of the vowel “a” (yawning).

8. “Blow the soup” breathing: While sitting, maximal inspiration was done through the nose, followed by expiration with mouth beak-shaped, as if blowing on soup. Variation: A maximal expiration was performed while simultaneously contracting the abdomen.

9. “Blow the candle” breathing: While sitting in front of a lit candle, maximal inspiration was done through the nose, followed by exhalation with mouth beak-shaped, blowing the candle flame just enough to bend it, without extinguishing it. Variation: The candle was placed at different distances, requiring greater control of expiratory flow. Slow expiration was performed while simultaneously contracting the abdomen.

10. “Lateral” breathing: While sitting, the left hand was placed on the right ribs; Inspiration was performed while tilting the torso to the left and extending the right arm straight over the head (the participant was instructed to “Feel the pressure” in the ribs under the left hand). This was followed by the return to starting position, with expiration. The same exercise was repeated for the opposite side.

11. Strong contraction of the abdomen: While standing, the participant slightly inclined the trunk forward and rested hands on semiflexed knees. A maximum expiration was done, followed by strong contraction of the abdomen and elevation of the diaphragm. This position was held for a few seconds, followed by inspiration and relaxation of the abdomen.

12. “Blocking” breathing: While sitting, a maximal inspiration was followed by a pause in breathing. The epiglottis was held closed, with head tilted, for as long as possible.

13. Oscillation of the trunk: While sitting, a maximum inspiration was followed by a pause. With bated breath, the chest and abdomen were alternately contracted and expanded, for a certain time, followed by a maximum expiration.

14. Pulmonary stimulation: While sitting, a maximum inspiration was followed by a pause. With bated breath, the chest was lightly slapped. Further inspiration was attempted, then the air was released through exhalation.

15. Breath expansion: While sitting, inspiration and expiration was done without pause. The same exercise was performed with one pause and then, with two pauses. Three pauses were attempted. The aim was to fractionate the breath with the pause and promote further expansion of the chest. Variation: At every pause, the breath was held and the abdomen was contracted one to three times.

16. “Jug” breathing: While sitting, one hand was placed on the abdomen and the other on the chest. Inspiration was done “by filling” the abdomen and then the chest. The expiration emptied the air first from the chest, then the abdomen.

17. “Semiblocked” breathing: While sitting, one nostril was blocked. Slow inhalation and exhalation was done through one nostril, followed by repeat with the other nostril.

18. “Fractionated” breathing: While sitting, breaths were taken in “small portions” (fractional) to the maximum filling of the lungs, followed by exhalation in small portions until complete emptying. The abdomen was simultaneously contracted with each exhalation.

19. “Total awareness” exercise: While sitting, breathing was done through the nose, by “filling the abdomen”; in the maximal pulmonary capacity the breath was blocked and then, the abdomen was contracted. After a pause, exhalation was done through the mouth with further contraction of the abdomen. At the end of exhalation, the abdomen was relaxed.

20. “Emptying the lungs”: While sitting, full exhalation was done through the mouth with simultaneous contraction of the abdomen. The breath was held and head tilted, and this position was maintained as long as possible. This was followed by a strong inspiration through the nose, while lifting the head and relaxing the abdomen.

In the third part of session, the volunteers performed inspiratory muscle training using the RESPIRON^® device (NCS Ltda, Barueri, SP, Brazil). This apparatus promotes resistance to the flow of inspired air. It consists of three cylinders that house balls (Figure S1). With inhalation through the mouthpiece, the balls rise as result of the effort (visual incentive). The respiratory training was conducted in a large, airy and quiet room. The volunteers performed the exercises sitting in a chair without arms.

Figure S2 shows the instructions for use of the RESPIRON^®. The exercises started at level “zero” (adjustment in the base of the first cylinder). After completing the exercises 1–6 at level 0, the level was changed to level 1 and the exercises performed again and so on, until level 3 was completed.

Social interaction group (the control group)

The participants performed activities such as painting, knitting, art with material recycled, tapestry, marquetry, embroidery, and origami. Each volunteer participated in three different activities per week. The activities were performed in a public senior living center.

Figure S1 Illustration of the exerciser and incentive spirometry

Note: Adapted with permission from the product manual (RESPIRON^®; NCS Ltda, Barueri, SP, Brazil).¹

Figure S2 Instructions for use of the RESPIRON^® (NCS Ltda, Barueri, SP, Brazil).

Notes: Extra instruction: Put adhesive labels on the air intake of cylinders 2 and 3 (front and back). Perform exercises 1–3. Then, remove the adhesive labels and perform exercises 1–6, at level 0.

Reference

• RESPIRON^® [Instruction Manual]BarueriNCS Indústria e Comércio de Equipamentos para Saúde, Ltda1997 Brazil
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