Determinants of lung function changes in athletic swimmers. A review

Risk profiles of elite breath-hold divers

This study aimed to determine a typical profile of elite breath-hold divers (BHDs), in relation to loss of consciousness (LOC) and episodic memory. Forty-four BHDs were evaluated during a world championship with anthropometric and physiological measurements, psychosociological factors and memory assessment. Seventy-five percent of the BHDs had at least one LOC with the predominance being men (p < 0.05). Thirty six percent of BHDs presented a low-risk profile and 64% a high-risk profile with no particular psychological pattern. Stepwise multiple linear regression showed that body fat, years of BH practice, age and forced vital capacity explained a significant amount of the variance of LOC for all BHDs (F(4,39) = 16.03, p < 0.001, R2 = 0.622, R2Adjusted = 0.583). No correlation was found between resting physiological parameters and their training or depth performances. In conclusion, anthropometric data, pulmonary factors and breath-holding experience were predictive of LOC in elite BHDs, with men taking more risks. BHDs episodic memory was not impaired.

The Puzzle of Marijuana Use and Forced Vital Capacity

In study after study, marijuana use has been found to be associated with increased forced vital capacity (FVC). This is puzzling, because marijuana is commonly consumed by inhalation of its smoke, and smoke exposure of any kind is not generally considered a cause of increased FVC. Although this observation was first made decades ago, a satisfactory explanation remains elusive. In this review we survey the evidence supporting the relationship between marijuana use and increased FVC, discuss potential threats to validity when inferring causation, and, presupposing a possible causal relationship, pose two key questions. First, what are possible physiologic or pathophysiologic mechanisms by which marijuana use might increase FVC? Second, why might this effect be consistently observed with marijuana use but not with tobacco use? Explanations for the first question include lung and chest growth and remodeling from strenuous marijuana smoke inhalation and reductions in lung elastic recoil from marijuana smoke exposure. Explanations for the second include differences between marijuana and tobacco in smoke composition and patterns of consumption, such as smoking topography. Finally, the possibility that smoke, whether from marijuana or tobacco, might have nonmonotonic effects on FVC depending on the degree of exposure is explored. In synthesizing a curated breadth of epidemiologic and physiologic science, we leverage a perplexing observation to generate potential insights and avenues for further research into the biological effects of smoke, from marijuana or otherwise, on the respiratory system.

PHYSICAL FUNCTION CHARACTERISTICS OF SWIMMERS IN PRE-COMPETITION TRAINING

ABSTRACT Introduction: Swimming is a competitive athletic activity whose fundamental objective is to produce high-performance athletes capable of standing out worldwide. Aerobic balance directly affects the athletic performance of these professionals. Objective: Investigate the changes in the physical composition and functional characteristics of swimmers before the competition. The results can play an important guiding role in the training plan of the Chinese athletics team in the competition. Methods: To explore the relationship between swimmers of different ages, the athletes were trained, and their physiological and chemical changes were monitored before the competition. A statistical, mathematical method was used to analyze the data. Results: After exercise, the swimmers’ hemoglobin, red blood cell count, hematocrit, creatine kinase, blood urea, and other indices had changed. The difference between the two groups was significant (P<0.05). Conclusion: The results showed that the swimmers’ body function was stable before the competition with better exercise load capacity. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

POTENTIAL PHYSICAL ENDURANCE TRAINING SYSTEM FOR SWIMMERS

ABSTRACT Introduction: Endurance and speed are fundamental to swimming. It is also essential for athletes to use the correct practice method during training to improve swimmers’ level of strength, endurance, and speed. Standardized swimming exercises can also reduce the inability of conventional land sports to adapt to the transition process from land to water. At the same time, standardized swimming exercises can also reduce the inability of conventional land sports to adapt to the transition process from land to water. This total swimming ability is also the goal pursued by many coaches and players. Objective: This study analyzes the training methods to improve swimmers’ strength, endurance, and speed. The results of this work can establish a theoretical basis for coaches to formulate training plans. Methods: This paper selects 20 swimmers as the object of research. There were ten males and ten females. All athletes participate in an endurance training program. This paper records the training intensity and endurance data during the athlete’s training. This paper uses mathematical statistics for data analysis. Results: The athletes’ human body’s technical level improved significantly after the endurance system exercise. The data were statistically significant (P<0.05). Conclusion: Endurance training can improve swimmers’ lower body strength. This training can make special training infinitely close to the demands of competition. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

CHANGES IN VO2MAX CAUSED BY AEROBIC EXERCISE IN SWIMMERS

ABSTRACT Introduction The maximal oxygen consumption rate (VO2max) can directly reflect the body's aerobic metabolism and oxygen delivery system. This is a measure of aerobic capacity used to monitor swimmers’ levels and their strength and speed performance. Objective Verify the changes in VO2max when incorporating aerobic exercise training into swimmers’ regular training. Methods 12 volunteer swimmers were divided into two categories: strength training group and regular training group. Both groups performed a fitness test on the 200-meter track before starting the training. VO2 maximal was measured and worked out statistically to verify the results of this competition. The effects of aerobic exercise on the strength and competitive status of the athletes were investigated according to an updated literature review. Results There was a significant change in the maximal oxygen uptake of the athletes after the experimental protocol. The athletes in the strength training group increased their VO2 max compared to the regular training group. The results showed a significant difference in the VO2max index before and after strength training (P<0.05). This suggests that strength training has a significant effect on maximal oxygen consumption. Conclusion Strength training interventions significantly affect athletes’ maximal oxygen consumption intensity and exercise capacity. The aerobic exercise intervention showed evidence of improving the competitive level of athletes. Level of evidence II; Therapeutic studies -investigation of treatment outcomes.

Modeling exercise using optogenetically contractible Drosophila larvae

The pathophysiological effects of a number of metabolic and age-related disorders can be prevented to some extent by exercise and increased physical activity. However, the molecular mechanisms that contribute to the beneficial effects of muscle activity remain poorly explored. Availability of a fast, inexpensive, and genetically tractable model system for muscle activity and exercise will allow the rapid identification and characterization of molecular mechanisms that mediate the beneficial effects of exercise. Here, we report the development and characterization of an optogenetically-inducible muscle contraction (OMC) model in Drosophila larvae that we used to study acute exercise-like physiological responses. To characterize muscle-specific transcriptional responses to acute exercise, we performed bulk mRNA-sequencing, revealing striking similarities between acute exercise-induced genes in flies and those previously identified in humans. Our larval muscle contraction model opens a path for rapid identification and characterization of exercise-induced factors.

Differences in lung function, bronchial hyperresponsiveness and respiratory health between elite athletes competing in different sports

Objectives: Examine lung function, bronchial hyperresponsiveness (BHR) and exercise-induced respiratory symptoms in elite athletes performing different sports.Methods: Norwegian national-team athletes (30 swimmers, 32 cross-country skiers, 16 speed-skaters, 11 rowers/paddlers, 17 handball players and 23 soccer players) completed a validated questionnaire, measured exhaled nitric oxide (FE_NO), spirometry, methacholine provocation (PD_20met) and skin prick test. Three cut-off levels defined BHR; i.e., PD_20met ≤2µmol, ≤4 µmol and ≤8µmol.Results: Mean forced vital capacity (FVC) was highest in swimmers (Mean z-score[95%CI] =1.16 [0.80, 1.51]), and close to or higher than reference values according to the Global Lung Initiative equation, across all sports. Mean forced expiratory volume in 1 second (FEV₁) was higher than reference values in swimmers (0.48 [0.13, 0.84]), and ball game athletes (0.69 [0.41, 0.97]). Mean forced expiratory flow between 25 and 75% of FVC (FEF_25-75), and/or FEV₁/FVC were lower than reference values in all endurance groups. BHR defined by ≤2 and ≤8 µmol methacholine was observed in respectively 50%-87% of swimmers, 25%-47% of cross-country skiers, 20%-53% of speed-skaters, 18%-36% and of rowers/paddlers, and 0%-17% of the ball game athletes. Exercise-induced symptoms were common in all groups, most frequent in cross-country skiers (88%), swimmers (83%) and speed-skaters (81%).Conclusion: Elite swimmers and ball game athletes had higher mean FVC and FEV₁, compared to reference values. However, FEF_25-75 and/or FEV₁/FVC was lower than the reference values in all endurance groups. The prevalence of BHR was high across all sports, except the ball game athletes, and most of the athletes reported exercise-induced respiratory symptoms.

Inhaled Marijuana and the Lung

Although vaping has recently increased as a mode of inhaling marijuana and has been associated with numerous and sometimes fatal cases of acute severe lung injury, smoking remains the most common method of inhaling marijuana and has been studied more extensively. Smoking marijuana has been shown to produce modest but significant short-term bronchodilation both in healthy subjects and those with asthma. Long-term effects of habitual marijuana smoking include the following: 1) symptoms of chronic bronchitis (increased cough, sputum production and wheezing); 2) modest effects on lung function in cross-sectional studies (no significant decrease in forced expired volume in 1 second [FEV₁) but mild reductions in FEV₁/forced vital capacity ratio [FEV₁/FVC], an increase in FVC and other lung volumes, reductions in specific airway conductance, and variable effects of maximal mid-expiratory flow rates and diffusing capacity; and 3) variable effects on age-related decline in FEV1 in longitudinal studies. Most cohort and case-control studies have failed to show that marijuana smoking is a significant risk-factor for lung cancer despite the presence of pro-carcinogenic components in marijuana smoke, although further study is warranted. The question whether marijuana smoking is associated with asthma is unclear and requires further investigation. Although delta-9 tetrahydrocannabinol (THC), the principal psychoactive component of marijuana, has immunomodulatory properties that hypothetically could increase the risk of pneumonia, the few available studies in marijuana smokers have failed to find an increased risk of pneumonia in immunocompetent users, although effects in immunosuppressed individuals have been variable.