Supplemental O 2 During Recovery Does Not Improve Repeated Maximal Concentric-Eccentric Strength-Endurance Performance in Hypoxia.

ABSTRACT: Dünnwald, T, Morawetz, D, Faulhaber, M, Gatterer, H, Birklbauer, C, Koller, A, Weiss, G, and Schobersberger, W. Supplemental O 2 during recovery does not improve repeated maximal concentric-eccentric strength-endurance performance in hypoxia. J Strength Cond Res 36(11): 3065-3073, 2022-An alpine ski racing training session typically includes repeated bouts of maximal exercise at high altitude. We evaluated whether hyperoxic recovery between 5 sets of high-intensity strength-endurance exercises, which resembled ski racing activity and were performed in hypoxia, has beneficial effects on performance and acid-base status. In this randomized, single blinded crossover study, 15 highly skilled ski athletes (4 f/11 m; 29.7 ± 5.7 years) performed 5 90 seconds flywheel sets (S) in a normobaric hypoxic chamber (3,500 m). The flywheel sets were separated by 4 15-minute recovery periods. During recovery, subjects received either 100% O 2 (hyperoxic setting [HS]) or hypoxic air (nonhyperoxic setting [NHS]; FiO 2 : 0.146). Performance outcomes (e.g., power output [PO], concentric peak power [Con peak ], and eccentric peak power [Ecc peak ]) and physiological parameters (e.g., heart rate, blood gases, and blood lactate) were evaluated. Mean PO, Con peak , and Ecc peak from S1 to S5 did not differ between settings (146.9 ± 45 W and 144.3 ± 44 W, 266.9 ± 80 W and 271.2 ± 78 W, and 271.0 ± 93 W and 274.1 ± 74 W for HS and NHS, respectively; p ≥ 0.05). SpO 2 , PaO 2 , and CaO 2 were higher during recovery in HS than in NHS ( p ≤ 0.001). Lactate levels were significantly lower in the last recovery phase in HS than in NHS ( p = 0.016). Hyperoxic recovery has no impact on performance in a setting resembling alpine ski racing training. Positive effects on arterial oxygen content and cellular metabolism, as indicated by reduced blood lactate levels during recovery in the hyperoxic setting, seem to be insufficient to generate a direct effect on performance.

Sex-Related Differences After a Single Bout of Maximal Eccentric Exercise in Response to Acute Effects: A Systematic Review and Meta-analysis.

Morawetz, D, Blank, C, Koller, A, Arvandi, M, Siebert, U, and Schobersberger, W. Sex-related differences after a single bout of maximal eccentric exercise in response to acute effects: a systematic review and meta-analysis. J Strength Cond Res 34(9): 2697-2707, 2020-The most prominent effects after unaccustomed eccentric exercise are muscle damage, muscle soreness, strength loss, and higher concentrations of muscle proteins in the plasma. The aim of this systematic review is to evaluate sex-related differences in these acute effects. A systematic literature search in MEDLINE following the PRISMA guidelines was performed. Inclusion criteria were the difference in absolute outcomes between sexes in eccentric muscle strength, strength loss after eccentric exercise, blood concentrations of creatine kinase (CK), and delayed onset muscle soreness (DOMS). Results for maximal eccentric torque and CK data were pooled using a random-effect meta-analysis. A meta-regression was conducted to explain heterogeneity. Based on the 23 included trials, men showed significantly higher absolute eccentric strength. No sex-related differences were detected when normalizing strength for body mass, cross-sectional area of the muscle, or fat-free mass. Women displayed a tendency toward greater relative strength loss immediately after exercise. The absolute CK concentrations of men were significantly higher after exercise-induced muscle damage. No significant difference was found between sexes in DOMS. Untrained men and women display similar responses in all measures of relative muscle strength and DOMS. Apart from the enzymatic activity after exercise and the levels of absolute eccentric torque, there is no evidence for sex-related differences immediately after eccentric exercise. Therefore, eccentric training might have the same impact on men and women. One potential sex difference with practical relevance would be the possible difference in fatigue pattern immediately after eccentric exercise.

The questionable benefit of pectus excavatum repair on cardiopulmonary function: a prospective study.

OBJECTIVES: Since the introduction of the minimally invasive technique for repair of pectus excavatum (MIRPE), increasing numbers of patients are presenting for surgery. However, controversy remains regarding cardiopulmonary outcomes of surgical repair. Therefore, the aim of our prospective study was to investigate cardiopulmonary function, at rest and during exercise before surgery, first after MIRPE and then after pectus bar removal. METHODS: Forty-seven patients were enrolled in a prospective, open-label, single-arm, single-centre clinical trial (Impact of Surgical Treatments of Thoracic Deformation on Cardiopulmonary Function) [NCT02163265] between July 2013 and November 2019. All patients underwent a modified MIRPE technique for surgical correction of pectus excavatum (PE), called Minor Open Videoendoscopically Assisted Repair of Pectus Excavatum. The patients underwent pre- and postoperative chest X-ray, three-dimensional volume-rendering computer tomography thorax imaging, cardiopulmonary function tests at rest and during stepwise cycle spiroergometry (sitting and supine position) and Doppler echocardiography. Daily physical activity questionnaires were also completed. RESULTS: The study was completed by 19 patients (15 males, 4 females), aged 13.9-19.6 years at the time of surgery. The surgical patient follow-up was 5.7 ± 7.9 months after pectus bar removal. No significant differences in cardiopulmonary and exercise parameters were seen after placement of the intrathoracic bar, or after pectus bar removal, compared to presurgery. CONCLUSIONS: Our findings indicate that surgical correction of PE does not impair cardiopulmonary function at rest or during exercise. Therefore, no adverse effects on exercise performance should be expected from surgical treatment of PE via the modified MIRPE technique. CLINICAL TRIAL REGISTRATION NUMBER: clinicaltrials.gov [ClinicalTrials.gov number, NCT02163265].

Impact of surgical treatment of pectus carinatum on cardiopulmonary function: a prospective study.

OBJECTIVES: The frequency of sternochondroplasty in cases of pectus carinatum (PC) has increased due to greater surgeon experience and modified surgical techniques. PC deformity does not usually cause cardiopulmonary malfunction or impairment. However, whether cardiopulmonary function changes after surgical repair remains a matter of controversy. The aim of our prospective study was to determine if surgery changes preoperative cardiopulmonary function. METHODS: Nineteen patients (16 males, 3 females) were enrolled in a prospective, open-label, single-arm, single-centre clinical trial (Impact of Surgical Treatments of Thoracic Deformation on Cardiopulmonary Function) (NCT02163265) between July 2013 and January 2017. All patients underwent PC repair via a modified Ravitch procedure and wore a lightweight, patient-controlled chest brace for 8 weeks postoperatively (the Innsbruck protocol). The average follow-up surgical examination was 8.3 months after surgery. In all enrolled patients, before surgery and not before 6 months postoperatively chest X-ray, 3-dimensional volume-rendered computed tomography thorax imaging, cardiopulmonary function tests with stepwise cycle spiroergometry (sitting and supine position) and Doppler echocardiography were performed; questionnaires about daily physical activity were also completed. RESULTS: Fourteen patients (aged 16.3 ± 2.6 years at study entry) completed the study. Changes in submaximal and peak power output were not detected during sitting, or when in the supine position. Also, no clinically relevant postoperative changes in spirometry or echocardiography were noted. CONCLUSIONS: Our findings confirm that surgical correction of PC does not impair cardiopulmonary function at rest or during physical exercise. CLINICAL REGISTRATION NUMBER: clinicaltrials.gov NCT02163265.

Can Hyperoxic Preconditioning in Normobaric Hypoxia (3500 m) Improve All-Out Exercise Performance in Highly Skilled Skiers? A Randomized Crossover Study.

BACKGROUND: The altering effects of hypoxia on aerobic/anaerobic performance are well documented and form the basis of this study. Application of hyperoxic gases (inspiratory fraction of oxygen [FiO2] > 0.2095) prior to competition or training (hyperoxic preconditioning) can compensate for the negative influence of acute hypoxia. PURPOSE: To investigate whether oxygen supplementation immediately prior to exercise (FiO2 = 1.0) improves all-out exercise performance in normobaric hypoxia (3500 m) in highly skilled skiers. METHODS: In this single-blind, randomized, crossover study, 17 subjects performed a 60-second constant-load, all-out test in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 minutes prior to the all-out test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times, and muscle oxygenation was assessed with near-infrared spectroscopy. RESULTS: Absolute and relative peak power (P = .073 vs P = .103) as well as mean power (P = .330 vs P = .569) did not significantly differ after the hyperoxic preconditioning phase. PaO2 increased from 51.3 (3) to 451.9 (89.0) mm Hg, and SaO2 increased from 88.2% (1.7%) to 100% (0.2%) and dropped to 83.8% (4.2%) after the all-out test. Deoxygenation (P = .700) and reoxygenation rates (P = .185) did not significantly differ for both preconditioned settings. CONCLUSIONS: Therefore, the authors conclude that hyperoxic preconditioning did not enhance 60-second all-out exercise performance in acute hypoxia (3500 m).

Impact of Hyperoxic Preconditioning in Normobaric Hypoxia (3500 m) on Balance Ability in Highly Skilled Skiers: A Randomized, Crossover Study.

It is well known that acute hypoxia has negative effects on balance performance. An attempt to compensate for the influence of hypoxia on competition performance was made by the application of hyperoxic gases (inspiratory fraction of oxygen > 0.2095) prior to exercise. PURPOSE: To investigate whether hyperoxic preconditioning (pure-oxygen supplementation prior to exercise) improves balance ability and postural stability during normobaric hypoxia (3500 m) in highly skilled skiers. METHODS: In this single-blind randomized, crossover study, 19 subjects performed a 60-s balance test (MFT S3-Check) in a normobaric hypoxic chamber. After a short period of adaptation to hypoxia (60 min), they received either pure oxygen or chamber air for 5 min prior to a balance test (hyperoxic preconditioning vs nonhyperoxic preconditioning). Capillary blood was collected 3 times. RESULTS: Balance performance, indexed by sensory (P = .097), stability (P = .937), and symmetry (P = .202) scores, was not significantly different after the hyperoxic preconditioning phase. Balance performance decreased over time (no group difference). After hyperoxic preconditioning, arterial partial pressure of oxygen increased from 52.7 (4.5) mm Hg to 212.5 (75.8) mm Hg, and oxygen saturation of hemoglobin increased from 85.8% (3.5%) to 98.9% (0.7%) and remained significantly elevated to 90.1% (2.0%) after the balance test. CONCLUSION: A hyperoxic preconditioning phase does not affect balance performance under hypoxic environmental conditions. A performance-enhancing effect, at least in terms of coordinative functions, was not supported by this study.

Feasibility of Ski Mountaineering for Patients Following a Total Knee Arthroplasty: A Descriptive Field Study.

Background: Total knee arthroplasty (TKA) is socially relevant due to its high prevalence, high incidence and the affected population. A subpopulation of TKA patients exists that strives to be active and also return to sports after total joint replacement. In this context, a further group of TKA patients is interested in high-impact physical activities and want to proceed with such activities even after surgery. Focusing on winter sports, there is still a lack of evidence on whether ski mountaineering is feasible for this subgroup of patients. Therefore, this feasibility study examines the effects of moderate ski mountaineering on strength, balance, functional abilities and mental health in persons following a TKA. Methods: Eight patients (six males, two females; median age, 63 ± Interquartile range 9 years) with TKA were included in this study. The volunteers, who were pre-selected for a 7-day holiday in Sankt Johann (Tyrol, Austria), participated in five guided ski mountaineering tours. Statistical analyses of non-parametric longitudinal data were performed using analysis of variance. For gait parameters and the Feeling Scale, one-factor longitudinal models were used. Statistical significance was set at the level of p < 0.05. Results: A significant decrease in the S3-Check MFT stability index (p = 0.04), a significant increase in general well-being (p = 0.05), and a trend towards a decrease in general stress (p = 0.1) were detected, while all other parameters were unaffected. Conclusion: A 7-day recreational ski mountaineering holiday had no negative effects on ski-experienced patients with TKA and seemed to increase well-being. Further studies should focus on larger groups and use controlled designs. Additionally, long-term effects should be evaluated.

Effects of Recreational Ski Mountaineering on Cumulative Muscle Fatigue - A Longitudinal Trial.

Sport is known to have many positive effects on mental and physical health. High-intensity exercise is considered to decrease muscle strength and induce muscle fatigue, which is associated with a higher risk of injury. In recreational alpine skiers, a decrease of eccentric peak hamstring torque, as an indication of muscle fatigue, occurs even after 1 day of skiing. The popularity of ski mountaineering is increasing enormously, but no studies are available on its effects on muscle strength. Therefore, the present study examined the consequences of ski mountaineering on muscle fatigue of the concentric/eccentric quadriceps and/or hamstrings. In addition, a possible role of myofascial foam rolling in reducing muscle fatigue was evaluated. Fifty recreational ski mountaineers (27 males, 23 females) completed five consecutive tours of ski mountaineering within 1 week. After each day of skiing, participants underwent an isokinetic muscle test assessing the concentric and eccentric muscle strength of both thighs. One group completed an additional session of myofascial foam rolling. Right and left concentric quadriceps peak torque, left hamstrings peak torque, left eccentric quadriceps peak torque, as well as right and left hamstring peak torque, were reduced after a single day of ski mountaineering (p ≤ 0.016 for all). However, no cumulative muscle fatigue was detected and we could not demonstrate any effect of myofascial foam rolling. The results show conclusively that a single day of ski mountaineering leads to a significant decrease of concentric and eccentric quadriceps and hamstring strength. Therefore, in order to improve muscle strength for the ski mountaineering season, a physical training program including concentric and eccentric methods can be recommended.

Why the emperor's new clothes are not made in Colombia? : A case study in Latin America and East Asia manufactured exports / Why the emperor's new clothes are not made in Colombia? : A case study in Latin America and East Asia manufactured exports

This study focusses on the exports of a particular commodity (clothing) from a particular Latin American country (Colombia) in an attempt to understand why Latin America has been so much less successful at exporting manufactured goods to date than East Asia. Part I analyzes and attempts to explain the curious pattern of Colombia's clothing exports during 1967-78. Part II delves in detail into the price and non-price reasons why Hong Kong, Korea and Taiwan, whose combined population is less than 2-1/2 times that of Colombia, export garments whose value is 150 times that of Colombia's clothing exports. Part III summarizes some of the main conclusions, draws out some policy options that are available to Colombia, and examines the extent to which the findings are generalizable to other manufacturing industries and other Latin American countries. The study was done under a World Bank research project, Marketing Manufactured Exports (671-56) (AU)