Sage Journals: Discover world-class research

Abstract

BACKGROUND:

An enthusiasm for physical exercise is often developed in the paediatric age group through collective game-based sporting activities. Regular exercise via sports can create positive effects on the respiratory systems of boys as well as on their overall growth and development. To help identify deviations from positive trends in these areas, respiratory function tests have become an essential part of the diagnosis and assessment of pulmonary disease.

OBJECTIVE:

To investigate the effect of different types of sports on pulmonary functions and respiratory muscle strength and to help establish baseline reference values in healthy Turkish boys aged 8–12 years.

METHODS:

A total of 624 healthy boys, who train at least twice a week for football (128), basketball (105), archery (60), swimming (111) and wrestling (74), as well as 146 boys who do not perform regular physical activities voluntarily, participated in the study. To evaluate and potentially differentiate amongst the merits of these several sports, we obtained a variety of baseline measurements from our subjects, including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, maximal peak expiratory flow (PEF max), maximal voluntary ventilation (MVV), maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP).

RESULTS:

There were statistically significant differences amongst the types of sports regarding the various metrics we examined: FVC, FEV1, FEV1/FVC, PEF max, MVV, MIP and MEP ( $p<$ 0.05). The active boys showed higher mean values for pulmonary functions and respiratory muscle strength than the passive ones. Also, the wrestlers generally had better respiratory parameters than those of athletes in the other four sports we investigated.

CONCLUSIONS:

It was clear that exercise, especially regarding pulmonary function and respiratory muscle strength, produced better outcomes in the active boys compared with our control group of relatively passive boys. The mechanisms responsible for this difference are likely due to the resistance effect of exercise.

Keywords

Pulmonary functions respiratory muscle strength boys exercise

1. Introduction

It is well known that the respiratory system is not fully developed in boys and that in this age category it generally has a weak structure, and as a result, many paediatric diseases involve respiratory conditions [1, 2]. The rapid development in paediatric medical science and technology has decreased the time required for the diagnosis and identification of respiratory tract diseases associated with factors such as infections and premature as well as congenital malformations, and this has enabled the development of new and effective treatment methods for many childhood illnesses [3]. Partly due to numerous innovative processes, scientists have developed special tools to invent new treatment approaches and diagnostic techniques for chronic respiratory system diseases which are increasing amongst boys, such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, as well as neuromuscular diseases, and to better identify those who are susceptible to acute and chronic diseases at an early stage.

The process of human adaptation to diseases of the pulmonary system has been objectively evaluated [2, 4, 5], and many studies have been conducted on different patient and age groups regarding respiration [6, 7, 8]. These efforts have shown that physical activity has a positive effect on pulmonary functions as well as on respiratory muscle strength for athletes and in adults generally [9, 10, 11, 12, 13]. Although there have been many investigations of respiratory system diseases in boys [7, 14, 15, 16, 17] only a limited number have addressed the effects of different types of exercises, sports and school levels, on their pulmonary functions, and especially on their development of respiratory muscle strength and endurance [1, 18].

Table 1
Descriptive characteristics of subjects

Variables	Swimming ( $n$ :111)		Basketball ( $n$ :105)		Football ( $n$ :128)		Wrestling ( $n$ :74)		Archery ( $n$ :60)		Inactive ( $n$ :146)		Total
Age (years)	9.91	(1.24)	9.74	(1.25)	10.03	(1.22)	10.82	(1.25)	10.43	(1.17)	9.3	(0.64)	9.92	(1.21)
Height (cm)	141.52	(16.42)	142.12	(9.86)	140.35	(8.45)	146.89	(10.7)	147.52	(10.72)	133.01	(6.32)	140.6	(11.63)
Weight (kg)	37.5	(8.85)	37.52	(9.6)	34.38	(7.56)	45.22	(15.79)	41.55	(10.57)	31.58	(6.85)	36.78	(10.49)
BMI (kg/m ${}^{2}$ )	18.24	(2.93)	18.35	(3.11)	18.6	(5.11)	20.49	(4.7)	18.88	(3.19)	17.72	(2.91)	18.54	(7.47)
Sports experience	2.45	(1.52)	1.96	(1.13)	2.28	(1.2)	1.57	(0.72)	1.25	(0.47)	–		1.54	(1.36)

$n=$ Sample size.

In light of this situation, we aimed to assess the pulmonary function and respiratory muscle strength in boys aged 8–12 years, and then to compare these findings amongst those who regularly play sports and those who do not. To our knowledge, this is the first study to directly address these questions across a variety of different sports, using a large number of subjects and to investigate the characteristics of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in healthy Turkish boys. We hypothesised that pulmonary function and respiratory muscle strength in boys who exercise regularly would be greater compared with those who do not actively engage in sporting activities. In addition, we aimed to measure and define standard values for respiratory parameters in healthy Turkish boys so that these results could serve as baseline values in future research projects.

2. Method

2.1 Subjects

A total of 624 healthy boys volunteered to participate in this study (Table 1). Their parents undertook a survey prior to the boys being enrolled and were queried with respect to any chronic or acute respiratory system diseases or severe injuries that the boys had. For all participants, a parent or guardian also provided written consent. The study was approved by the Clinical Research Ethics Committee of Ondokuz Mayıs University.

2.2 Experimental design

This study analysed respiration muscle strength and pulmonary functions in boys who are actively playing five types of sports (football, basketball, wrestling, archery, swimming) and then compared these results with values obtained from boys who did not engage in these activities. To this end, our subjects visited the laboratory two times. During the first visit, they were informed about the test protocols, a pilot application was performed to help them understand how the study would progress, and their height, weight and body mass index (BMI) were measured. During the second visit, pulmonary function and respiratory muscle strength tests were performed. The subjects were asked to not engage in physical activity for at least several hours prior to their measurement sessions. This investigation was designed and implemented in accordance with the Declaration of Helsinki.

2.3 Procedures

2.3.1 Pulmonary function assessment

Pulmonary function measurements were performed using a spirometer (CPFS/D USB Spirometer, MGC Diagnostics, Saint Paul, MN, USA). Forced vital capacity (FVC), forced expiration volume in one second (FEV1), the FEV1/FVC ratio, maximal peak expiratory flow (PEF max) and maximal voluntary ventilation (MVV) were recorded using this pulmonary function test. The best measurements for each subject were used in the subsequent analyses.

2.3.2 Respiratory muscle strength

MIP and MEP were measured with a portable hand-held mouth respiratory pressure meter (MicroRPM, CareFusion Micro Medical, Kent, UK). After the appropriate filters and holders were fixed, the nasal airway was closed with a clip. The MIP measurement started with the residual volume, and MEP assessment began with total lung capacity. Measurements were performed three times, and the best value was recorded.

2.4 Statistical analysis

Statistical analyses of the data generated were performed using SPSS version 22.0 (SPSS Inc., Chicago, Illinois, USA). Values are presented as means, standard deviations and effect sizes. The Kolmogorov – Smirnov test was used to evaluate normality before the statistical operations. Multivariate (MANOVA) tests were used for comparisons amongst the sports. In the multiple comparison tests, the Tukey and Tamhane tests were used according to the homogeneity distributions of the variances. The effect sizes were obtained from partial eta-squared data. Significance was defined as $p\leqslant$ 0.05.

3. Results

Age, height, weight, BMI and sports experience data are presented in Table 1. Our comparison of pulmonary functions and respiratory muscles across the five sports is presented in Table 2. Statistically significant differences were found for FVC, FEV1, PEF max, MVV, MIP and MEP ( $p<$ 0.05). Across all these metrics, subjects specialised in wrestling and archery had higher average values than athletes in other sports and much higher values than those who did not actively engage in any sports activities.

Table 2
Analysis of pulmonary function and respiratory muscle strength measurements

Variables		Mean (s.d.)	SE	$p$	e.s.	95% CI
						LB		UB
FVC (L)	Swimming	2.26 ${}^{\rm b}$ (0.56)	0.05	$<$ 0.001	0.280	2.	16	2.	37
	Basketball	2.15 ${}^{\rm b}$ (0.42)	0.04			2.	07	2.	23
	Football	2.10 ${}^{\rm b}$ (0.39)	0.03			2.	04	2.	17
	Wrestling	2.59 ${}^{\rm c}$ (0.60)	0.07			2.	45	2.	73
	Archery	2.28 ${}^{\rm b}$ (0.50)	0.06			2.	15	2.	41
	Inactive	1.69 ${}^{\rm a}$ (0.23)	0.02			1.	65	1.	73
FEV1 (L)	Swimming	2.06 ${}^{\rm b,c}$ (0.46)	0.04	$<$ 0.001	0.282	1.	98	2.	15
	Basketball	1.99 ${}^{\rm b}$ (0.36)	0.04			1.	92	2.	06
	Football	1.96 ${}^{\rm b}$ (0.35)	0.03			1.	90	2.	02
	Wrestling	2.34 ${}^{\rm d}$ (0.47)	0.05			2.	23	2.	45
	Archery	2.16 ${}^{\rm c}$ (0.49)	0.06			2.	03	2.	29
	Inactive	1.59 ${}^{\rm a}$ (0.20)	0.02			1.	56	1.	62
FEV1/FVC (%)	Swimming	92.02 ${}^{\rm a,b}$ (7.73)	0.73	0.002	0.030	90.	56	93.	47
	Basketball	92.38 ${}^{\rm a,b}$ (7.45)	0.73			90.	94	93.	82
	Football	93.15 ${}^{\rm a,b}$ (6.55)	0.58			92.	00	94.	29
	Wrestling	90.85 ${}^{\rm a}$ (7.08)	0.82			89.	21	92.	49
	Archery	94.72 ${}^{\rm b}$ (5.72)	0.74			93.	24	96.	19
	Inactive	94.58 ${}^{\rm b}$ (8.21)	0.68			93.	24	95.	92
PEF max (L/s)	Swimming	289.40 ${}^{\rm b}$ (63.00)	5.98	$<$ 0.001	0.484	277.	55	301.	25
	Basketball	283.88 ${}^{\rm b}$ (57.35)	5.60			272.	78	294.	97
	Football	285.64 ${}^{\rm b}$ (51.71)	4.57			276.	60	294.	68
	Wrestling	328.32 ${}^{\rm c}$ (59.22)	6.88			314.	60	342.	04
	Archery	314.68 ${}^{\rm c}$ (53.27)	6.88			300.	92	328.	44
	Inactive	177.51 ${}^{\rm a}$ (44.41)	3.68			170.	24	184.	77
MVV (L/min)	Swimming	80.78 ${}^{\rm c}$ (17.51)	1.66	$<$ 0.001	0.205	77.	49	84.	08
	Basketball	77.48 ${}^{\rm b,c}$ (17.00)	1.66			74.	19	80.	77
	Football	72.77 ${}^{\rm b}$ (15.23)	1.35			70.	10	75.	43
	Wrestling	88.80 ${}^{\rm d}$ (19.44)	2.26			84.	29	93.	30
	Archery	80.25 ${}^{\rm c}$ (19.95)	2.57			75.	10	85.	40
	Inactive	63.57 ${}^{\rm a}$ (8.00)	0.66			62.	26	64.	88
MIP (cmH ${}_{2}$ O)	Swimming	80.43 ${}^{\rm a}$ (26.18)	2.49	$<$ 0.001	0.087	75.	51	85.	36
	Basketball	78.27 ${}^{\rm a}$ (20.23)	1.97			74.	35	82.	18
	Football	78.01 ${}^{\rm a}$ (21.47)	1.90			74.	25	81.	76
	Wrestling	94.89 ${}^{\rm b}$ (26.35)	3.06			88.	79	101.	00
	Archery	80.20 ${}^{\rm a}$ (26.41)	3.41			73.	38	87.	02
	Inactive	71.85 ${}^{\rm a}$ (8.07)	0.67			70.	53	73.	17
MEP (cmH ${}_{2}$ O)	Swimming	89.50 ${}^{\rm a,b}$ (23.18)	2.20	$<$ 0.001	0.113	85.	13	93.	86
	Basketball	89.69 ${}^{\rm a,b}$ (20.71)	2.02			85.	68	93.	69
	Football	92.39 ${}^{\rm a,b}$ (20.96)	1.85			88.	73	96.	06
	Wrestling	110.27 ${}^{\rm c}$ (27.50)	3.20			103.	90	116.	64
	Archery	95.98 ${}^{\rm b}$ (23.49)	3.03			89.	91	102.	05
	Inactive	86.16 ${}^{\rm a}$ (3.50)	0.29			85.	58	86.	73

${}^{\rm a,b,c,d}$ Means within the same column with different supercripts differ significantly; $p=$ results of Multivarate $p<$ 0.05; s.d. $=$ standart deviatons; e.s. $=$ Eta effect size; CI $=$ confidence of interval; LB $=$ lower bound; UB $=$ upper bound; FVC $=$ forced vital capacity; FEV1 $=$ forced expiratory volume in one second; PEF max $=$ maximal peak expiratory flow; MVV $=$ maximal voluntary ventilation; MIP $=$ maximal inspiratory pressure; MEP $=$ maximal expiratory pressure.

4. Discussion

This study aimed to investigate the effect of sports in general, and also five specific sports, on pulmonary functions and respiratory muscle strength in healthy Turkish boys between 8 and 12 years old. For this purpose, we conducted research on 624 healthy boys and generated three significant results: (1) the pulmonary functions and respiratory muscle strength of boys engaged in sports were significantly superior compared with those who were not involved with these activities, (2) the respiratory parameters of boys wrestlers were higher than those engaged in the other four sports we investigated and (3) we established standard reference values that can be used for future studies of healthy Turkish boys.

Numerous studies have revealed that in boys, factors such as age, height, weight [2, 4, 19] and physical activity level affect pulmonary functions and respiratory muscle strength [18, 20, 21, 22, 23]. It is also well known that boys who are overweight or obese or who have significant health problems, such as scoliosis, have lower pulmonary function [22, 23, 24].

In the present study, it was observed that the average values of respiratory muscle strength and function of boys aged 8–12 years differ with respect to the sports they played and that those who regularly engage in sports have better values compared with those who do not. We also found that wrestlers have better respiratory function values compared with players of the other sports we included in this study ( $p<$ 0.05). Generally, it has been reported that in athletes performing combat sports, such as judo and wrestling, muscles related to the core region and respiration develop more, and as a result, they have higher respiratory parameters compared with athletes engaged in other sports [25].

We found that the average values regarding the pulmonary function and respiratory muscle strength of athletes in the fields of swimming, football and basketball are higher than those who do not actively engage in these activities. This finding can be explained by their aerobic exercise during training as it is well known that people who undertake intense aerobic activities have relatively high endurance gains in both respiratory and locomotor muscles and that their hyperpnoea levels peak, resulting in comparatively higher levels of pulmonary function and respiratory muscle strength [1]. Additionally, constant stress applied on the muscles during an aerobic performance causes changes in mitochondrial and enzyme activity, especially in the diaphragm, which in turn increases the resistance against the oxygenation of respiratory muscles and fatigue [26]. This study showed that wrestlers, followed by archers, had better averages in these two metrics compared with other athletes studied. In archery, the strength and durability of the upper extremity and core muscles are directly associated with better performance [27]. It has been shown that the training procedures used in archery do not cause significant stress on the respiratory system [28]. It is also known that the lung capacity of archers is generally larger than for athletes in other sports [29]. Moreover, studies have revealed that archers have superior cardiovascular systems and better metrics regarding breathing and blood pressure compared with other athletes [28]. A successful shot in archery usually involves the highly effective use of breathing control and other pulmonary functions. Moreover, the special breathing exercises that are regularly included in the training of archers are likely the reason for their superior respiratory parameters compared with other athletes.

The different types of training systems used by athletes in various sports are significant factors helping to generate often substantial differences in the physiological development of boys [30, 31, 32, 33]. Although the best pulmonary and cardiovascular values produced in our study were acquired from wrestlers, it was found that the respiratory systems of swimmers and archers were also relatively well developed. Although it is known that the aerobic system can be improved in football and basketball like it is in swimming, a substantial literature now shows that both paediatric and adult swimmers have stronger values relating to pulmonary and cardiac function compared with athletes [1, 34]. This result is likely produced because the respiratory system of swimmers is under massive stress as they ventilate while performing in a horizontal position with the help of the buoyancy of water, enabling them to exert extraordinary levels of muscular strength and endurance over substantial lengths of time, even compared with the strenuous demands of many other sports [35].

In conclusion, it is widely thought that the differences in respiratory parameters of boys playing different sports differ by age, height, weight and sports experience. The central hypothesis of the current study, namely that the pulmonary function and respiratory muscle strength of boys performing regular exercise will be greater compared with inactive boys, was borne out. We found that athletes specialised in the five sports we examined had higher parameter values than boys who did not significantly engage in athletic activities. The mechanism producing this result is thought to be the positive effect of increased respiratory muscle strength on lung volume and capacity due to the resistance effect of exercise. It is believed that athletes in sports involving a substantial aerobic component have higher pulmonary function values. However, the impact of different sports is more marked in adults compared with boys due to the lower level of sports experience and the relatively incomplete physical development of the much younger athletes.

Similar studies on boys from various countries would be helpful in terms of determining baseline values for comparison. It is believed that physical activity starting at early ages would play a preventative role against chronic respiratory tract diseases, both during childhood and throughout the adult years, and moreover, that regular exercise in boys with respiratory tract diseases would have a significant positive effect on their quality of life.

Footnotes

Acknowledgments

Our study entitled “The differential impact of several types of sports on pulmonary functions and respiratory muscle strength in boys aged 8–12” was conducted with support from Project 1901 of Ondokuz Mayıs University Scientific Research and Development Program (PYO.YDS.1901.16.004).

Conflict of interest

None to report.

References

Santos

MLDMD

Rosa

Ferreira

CDR

Medeiros

ADA

Batiston

. Maximal respiratory pressures in healthy boys who practice swimming or indoor soccer and in healthy sedentary boys. Physiotherapy Theory and Practice. 2012; 28(1): 26-31.

Tomalak

Pogorzelski

Prusak

. Normal values for maximal static inspiratory and expiratory pressures in healthy boys. Pediatric Pulmonology. 2002; 34: 42-46.

Jones

. Manobras expiratórias forçadas em lactentes. J Pneumol. 2002; 28(Supl 3): 223.

Choudhuri

Aithal

Kulkarni

. Maximal expiratory pressure in Residential and Non-Residential school boys. The Indian Journal of Pediatrics. 2002; 69(3): 229-232.

Tomalak

Radliński

Pogorzelski

Doniec

. Reference values for forced inspiratory flows in boys aged 7–15 years. Pediatric Pulmonology. 2004; 38(3): 246-249.

Parreira

França

Zamp

Fonseca

Tomich

Britto

. Maximal respiratory pressures: actual and predicted values in healthy subjects. Brazilian Journal of Physical Therapy. 2007; 11(5): 361-368.

Fiore Junior

Paisani

DDM

Franceschini

Chiavegat

Faresi

. Maximal respiratory pressures and vital capacity: comparison mouthpiece and face-mask evaluation methods. Jornal Brasileiro de Pneumologia. 2004; 30(6): 515-520.

Lanteri

Sly

. Changes in respiratory mechanics with age. Journal of Applied Physiology. 1993; 74(1): 369-378.

Kroff

Terblanche

. The kinanthropometric and pulmonary determinants of global respiratory muscle strength and endurance indices in an athletic population. European Journal of Applied Physiology. 2010; 110(1): 49-55.

10.

Volianitis

McConnell

Koutedakis

McNaughton

Backx

Jones

. Inspiratory muscle training improves rowing performance. 2001.

11.

Romer

Mc Connell

Jones

. Effects of inspiratory muscle training on time-trial performance in trained cyclists. Journal of Sports Sciences. 2002; 20(7): 547-590.

12.

Lomax

Tasker

Bostanci

. Inspiratory muscle fatigue affects latissimus dorsi but not pectoralis major activity during arms only front crawl sprinting. The Journal of Strength & Conditioning Research. 2014; 28(8): 2262-2269.

13.

Özdal

Bostanci

Dağlioğlu

Ağaoğlu

Kabadayi

. Effect of respiratory warm-up on anaerobic power. Journal of Physical Therapy Science. 2016; 28(7): 2097-2098.

14.

Garg

Bhargava

Pooni

Das

Mishra

. Follow-up assessment of pulmonary functions in mechanically ventilated boys after discharge from pediatric intensive care unit: A developing country perspective. Indian Journal of Child Health. 2017; 4(4): 471-477.

15.

Alpaslan

Ucok

Coşkun

KŞ

Genc

Karabacak

Guzel

. Resting metabolic rate, pulmonary functions, and body composition parameters in boys with attention deficit hyperactivity disorder. Eating and Weight Disorders-Studies on Anorexia, Bulimia and Obesity. 2017; 22(1): 91-96.

16.

Takagi

Nakase

Miyasaka

Onodera

. Changes in Pulmonary Functions in Individuals with or without Past Medical Histories of Bronchial Asthma during Physical Education Classes in Summer and Winter International. Journal of Sport and Health Science. 2018; 20(17): 4.

17.

Çelik

Karakurt

Acar

Çelik

. Rapid Improvement of Pulmonary Functions in Boys After Transcatheter Closure of an Atrial Septal Defect. Pediatric Cardiology. 2018; 39(2): 329-334.

18.

Heinzmann-Filho

Vidal

PCV

Jones

Donadio

MVF

. Normal values for respiratory muscle strength in healthy preschoolers and school boys. Respiratory Medicine. 2012; 106(12): 1639-1646.

19.

Peterson-Carmichael

Seddon

Cheifetz

Frerichs

Hall

Hammer

Pillow

. An official American thoracic society/european respiratory society workshop report: Evaluation of respiratory mechanics and function in the pediatric and neonatal intensive care units. Annals of the American Thoracic Society. 2016; 13(2): 1-11.

20.

Choi

Shin

Jang

Lee

Kim

Shin

. Maximal Inspiratory Pressure and Maximal Expiratory Pressure in Healthy Korean Boys. Annals of Rehabilitation Medicine. 2017; 41(2): 299-305.

21.

Arnall

Nelson

Owens

Iranzo

MDÀCI

Sokell

Kanuho

Coast

. Maximal respiratory pressure reference values for Navajo boys ages 6–14. Pediatric Pulmonology. 2013; 48(8): 804-808.

22.

Junior

Peixoto-Souza

Araujo

Barbalho-Moulin

Alves

Gomes

Costa

. Influence of body composition on lung function and respiratory muscle strength in boys with obesity. Journal of Clinical Medicine Research. 2016; 8(2): 105.

23.

Black

Hyatt

. Maximal respiratory pressures: normal values and relationship to age and sex. American Review of Respiratory Disease. 1969; 99(5): 696-702.

24.

Rosa

GJD

Schivinski

CIS

. Assessment of respiratory muscle strength in boys according to the classification of body mass index. Revista Paulista de Pediatria. 2014; 32(2): 250-255.

25.

Radovanovic

Bratic

Nurkic

Stankovic

. Recovery of dynamic lung function in elite judoists after short-term high intensity exercise. Archives of Budo. 2011; 7(1): 21-26.

26.

Coast

Clifford

Henrich

Stray-Gundersen

JAMES

Johnson

. Jr. Maximal inspiratory pressure following maximal exercise in trained and untrained subjects. Medicine and Science in Sports and Exercise, 1990; 22(6): 811-815.

27.

Humaid

. Influence of arm muscle strength, draw length and archery technique on archery achievement. Asian Social Science. 2014; 10(5): 28.

28.

McArdle

Katch

. Exercise physiology: nutrition, energy, and human performance. 2010, Lippincott Williams & Wilkins.

29.

Thakare

. Comparative study of peak expiratory flow rate of archery players participated in all India inter university archery competition. International Journal of Physical Education, Sports and Health. 2015; 2(2): 331-332.

30.

Faigenbaum

Kang

Ratamess

Farrell

Ellis

Vought

Bush

. Acute Cardiometabolic Responses to Medicine Ball Interval Training in Boys International. Journal of Exercise Science. 2018; 11(4): 886-899.

31.

Granacher

Lesinski

Büsch

Muehlbauer

Prieske

Puta

Behm

. Effects of resistance training in youth athletes on muscular fitness and athletic performance. 2018.

32.

Kojima

Brammer

Sossong

Abe

Stager

. In-Water Resisted Swim Training for Age-Group Swimmers: An Evaluation of Training Effects. Pediatric Exercise Science. 2018; 30(1): 124-131.

33.

Ohya

Hagiwara

Chino

Suzuki

. Maximal inspiratory mouth pressure in Japanese elite male athletes. Respiratory Physiology & Neurobiology. 2016; 230: 68-72.

34.

Cordain

Tucker

Moon

Stager

. Lung volumes and maximal respiratory pressures in collegiate swimmers and runners. Research Quarterly for Exercise and Sport. 1990; 61(1):70-74.

35.

Lomax

McConnell

. Inspiratory muscle fatigue in swimmers after a single 200 m swim. Journal of sports sciences. 2003; 21(8): 659-664.

The differential impact of several types of sports on pulmonary functions and respiratory muscle strength in boys aged 8–12

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

Table 1 Descriptive characteristics of subjects

2.1 Subjects

2.2 Experimental design

2.3 Procedures

2.3.1 Pulmonary function assessment

2.3.2 Respiratory muscle strength

2.4 Statistical analysis

3. Results

Table 2 Analysis of pulmonary function and respiratory muscle strength measurements

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Descriptive characteristics of subjects

Table 2
Analysis of pulmonary function and respiratory muscle strength measurements