The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or of certain manufacturers' products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. All reasonable precautions have been taken by the World Health Organization to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use.

Pind, R, Mäestu, E, Purge, P, Jürgenson, J, Arend, M, and Mäestu, J. Internal load from hard training sessions is related to changes in performance after a 10-week training period in adolescent swimmers. J Strength Cond Res 35(10): 2846–2852, 2021—The purpose of this study was to investigate the association between session rating of perceived exertion (sRPE) and its categorization with the changes in swimming performance in adolescent swimmers. National level swimmers (age 16.4 ± 2.1 years, V̇o 2max 50.0 ± 4.0 ml·min−1·kg−1) participated in a 10-week period preceding the National Winter Championships. Pre-training and post-training physiological parameters and swimming performance were measured. All training bouts with sRPE data were recorded. In addition, trainings were categorized as light, moderate, or hard. For calculating the corresponding internal training load (ITL), 2 fixed categorizations were applied based on earlier published sources and an individualized categorization based on ventilatory thresholds. During the 10-week training period, large to very large increases were found in aerobic (effect size [ES] = 1.58) and anaerobic threshold power output W·kg−1 (ES = 2.46), respectively, and smaller, but significant, improvement in 100-m swimming performance (ES = 0.36). Total ITL during the 10-week period was significantly related to changes in anaerobic threshold (r = 0.81). Fixed and individualized sRPE methods from hard sessions were associated with changes in V̇o 2max (r = 0.77) and performance of only 100-m leg kicks (r = 0.76), respectively. Internal training load was related to changes in performance variables during the 10-week study period. Using individualized sRPE values, the accumulation of the ITL from hard training sessions was associated with changes in V̇o 2max and swimming performance. The aforementioned categorization could help coaches in appropriate application of ITL for assessing the total training load in adolescent swimmers.

The aim of this study was to determine the lifetime prevalence and point prevalence of low back pain (LBP), the related pain intensity and the rowing-related aggravating factors for LBP in Estonian rowers. A total of 78 rowers (38 female and 40 male subjects) completed a single questionnaire at the start of the competitive rowing season to determine lifetime and point prevalence, pain intensity and rowing-related LBP aggravating factors. The lifetime prevalence was high in both male and female rowers (90% and 93%, respectively), and the reported point prevalence of LBP was 10% in males and 21.1% in females. Female rowers reported significantly higher (p=0.02) LBP intensity when training 7-16 hours per week, when compared to females whose training volume was less than six hours per week. Rowing-related LBP aggravated factors were long rowing workouts, weight training and sitting for a long period of time. LBP is highly prevalent in rowers and female rowers seemed to be more prone to developing higher intensity LBP when training loads increased. Coaches should cooperate more with sports medicine specialists to better prepare female athletes core endurance to tolerate longer duration rowing workouts and prevent LBP.

Aim: The purpose of this study was to evaluate the effect of a pre-seasonal 12-week supervised strength training program (SSTP) on arterial stiffness, brachial and central blood pressure, and systolic and diastolic function of the heart in elite powerlifting athletes. Methods: A descriptive study was performed in 19 elite male powerlifters, who exercised for 12 weeks, four days per week with an intensity of 60-90% assessed from 1 repetition maximum and 90-120 min per session. Carotid-femoral pulse wave velocity (cfPWV), augmentation index and central blood pressure were measured by applanation tonometry using the SphygmoCor device, and an echocardiographic examination was performed at baseline and after 12-week SSTP. Results: Subjects' mean brachial and central systolic blood pressure decreased significantly after the training period (132.3±8.8 vs 124.3±8.7 mmHg, p=0.002 and 110.1±7.7 vs 104.5 ±8.7 mmHg, p=0.008, respectively). Strength training significantly improved systolic tricuspid annular velocity and mitral E/e' ratio (p<0.05). There were no significant differences in cfPWV and augmentation index at baseline and after SSTP. Conclusion: The 12-week supervised strength pre-seasonal training program significantly decreased brachial and central systolic blood pressure in male elite powerlifting athletes. The strength training program decreased left ventricular filling pressure and improved right ventricular systolic function. No significant effect of strength training on aortic stiffness was found.

There is no clear understanding about the effect of intensive physical load on arterial stiffness and related biomarkers. The aim of this study was to evaluate the effect of half-marathon running on arterial stiffness and blood biomarkers during post-competitive recovery period in competitive and recreational male athletes. Eleven high-level long-distance runners (27.1 ± 4.8 yrs) and seven recreational athletes (34.3 ± 6.1 yrs), who participated in a half-marathon run were examined. Blood biomarkers and arterial stiffness (SphygmoCor 7.1) were measured at baseline and at 18 to 22 hours after the competition. There were no statistically significant changes between the groups in augmentation index (AIx, AIx@75) or pulse wave velocities at carotid-femoral segment (cfPWV) during recovery period. Between-group comparison did not reveal significant differences in blood pressure and arterial stiffness values at baseline and during recovery period. The change of cfPWV (difference between cfPWV at baseline and cfPWV during post-competitive recovery period) was significantly dependent on race time and sports level of the athlete (high-level or recreational). A significant increase was found in hsCRP, creatine kinase and LDH activity during the post-race period in both groups. No significant changes were found in oxidative stress markers in the groups after the race except for higher diene conjugates level in recreational athletes in comparison with the high-level group during recovery period. Our study results showed that half-marathon competition did not cause any significant changes in arterial stiffness parameters during the recovery period. However, the change in cfPWV was independently associated with half-marathon race time and the athlete’s level of training revealing a mild increase of arterial stiffness in high-level athletes and athletes with a faster race time.