Hip and core exercise programme prevents running-related overuse injuries in adult novice recreational runners: a three-arm randomised controlled trial (Run RCT).

OBJECTIVE: This study aims to investigate the efficacy of two exercise interventions in reducing lower extremity (LE) injuries in novice recreational runners. METHODS: Novice runners (245 female, 80 male) were randomised into hip and core (n=108), ankle and foot (n=111) or control (n=106) groups. Interventions were completed before running and included exercise programmes focusing on either (1) hip and core or (2) ankle and foot muscles. The control group performed static stretching exercises. All groups were supervised by a physiotherapist and performed the same running programme. Injuries and running exposure were registered using weekly questionnaires during the 24-week study. Primary outcome was running-related LE injury. RESULTS: The incidence of LE injuries was lower in the hip and core group compared with the control group (HR 0.66; 95% CI 0.45 to 0.97). The average weekly prevalence of overuse injuries was 39% lower (prevalence rate ratio, PRR 0.61, 95% CI 0.39 to 0.96), and the prevalence of substantial overuse injuries was 52% lower (PRR 0.48, 95% CI 0.27 to 0.90) in the hip and core group compared with the control group. No significant difference was observed between the ankle and foot group and control group in the prevalence of overuse injuries. A higher incidence of acute injuries was observed in the ankle and foot group compared with the control group (HR 3.60, 95% CI 1.20 to 10.86). CONCLUSION: A physiotherapist-guided hip and core-focused exercise programme was effective in preventing LE injuries in novice recreational runners. The ankle and foot programme did not reduce LE injuries and did not protect against acute LE injuries when compared with static stretching.

The Effects of an Intensive 2-wk Resistance Training Period on Strength Performance and Nocturnal Heart Rate Variability.

PURPOSE: It is known that modifying the endurance-type training load of athletes may result in altered cardiac autonomic modulation that may be estimated with heart rate variability (HRV). However, the specific effects of intensive resistance-type training remain unclear. The main aim of this study was to find out whether an intensive 2-wk resistance training period affects the nocturnal HRV and strength performance of healthy participants. METHODS: Young healthy men (N = 13, age 24 [2] y) performed 2-wk baseline training, 2-wk intensive training, and a 9-d tapering periods, with 2, 5, and 2 hypertrophic whole-body resistance exercise sessions per week, respectively. Maximal isometric and dynamic strength were tested at the end of these training periods. Nocturnal HRV was also analyzed at the end of these training periods. RESULTS: As a main finding, the nocturnal root mean square of differences of successive R-R intervals decreased (P = .004; from 49 [18] to 43 [15] ms; 95% CI, 2.4-10.4; effect size = 0.97) during the 2-wk intensive resistance training period. In addition, maximal isometric strength improved slightly (P = .045; from 3933 [1362] to 4138 [1540] N; 95% CI, 5.4-404; effect size = 0.60). No changes were found in 1-repetition-maximum leg press or leg press repetitions at 80% 1-repetition maximum. CONCLUSIONS: The present data suggest that increased training load due to a short-term intensive resistance training period can be detected by nocturnal HRV. However, despite short-term accumulated physiological stress, a tendency of improvement in strength performance was detected.

Physiological Load and Psychological Stress During a 24-hour Work Shift Among Finnish Firefighters.

OBJECTIVE: The aim of this study was to describe physiological load and psychological stress of Finnish firefighters during a 24-hour work shift. METHODS: R-R intervals were recorded during 24-hour work shifts. Short-time Fourier transform was used to analyze heart rate variability during shifts. RESULTS: HRmean, HRpeak, and square root of the mean of the sum of the squares of the differences between adjacent R-to-R peak intervals of the 24-hour shift was 73 ±â€Š7 bpm (38 ±â€Š4% of HRmax), 156 ±â€Š16 bpm (82 ±â€Š8% of HRmax), and 42 ±â€Š14 ms. Mean VO2 was 11 ±â€Š2 (% of VO2max) and VO2peak 72 ±â€Š11 (% of VO2max). CONCLUSIONS: Physiological load and psychological stress were temporarily high, even in young, fit firefighters. As the relative work load may increase and recovery processes slow down among aging employees, fatigue may occur unless work arrangements are well-designed.

Heart rate variability is related to training load variables in interval running exercises.

Overload principle of training states that training load (TL) must be sufficient to threaten the homeostasis of cells, tissues, organs and/or body. However, there is no "golden standard" for TL measurement. The aim of the present study was to investigate if post-exercise heart rate variability (HRV) could be used to evaluate TL of interval running exercises with different intensities and durations. Thirteen endurance-trained men (35 ± 5 years) performed MO(250) [moderate intensity, 2 × 6 × 250 m/rec 30 s/5 min at 85% of the maximal velocity of the graded maximal test (V (max))], MO(500) (2 × 3 × 500 m/rec 1 min/5 min at 85% V (max)) and HI(250) (high intensity, 2 × 6 × 250 m/rec 30 s/5 min at 105% V (max)) interval exercises on a treadmill. HRV was analyzed during rest, exercise and immediate 15 min recovery. Fast recovery of LFP (P < 0.001), HFP (P < 0.01) and TP (P < 0.01) occurred during the first two recovery minutes after each exercise. Strong negative correlations (P < 0.01) were found between post-exercise HRV and perceived exertion as well as excess post-exercise oxygen consumption. Post-exercise HRV differentiated interval exercises of equal work, but varying intensity or distance of running bout. The results of the present study suggest that immediate post-exercise HRV may offer objective information on TL of interval exercises with different bout durations and intensities.

Can HRV be used to evaluate training load in constant load exercises?

The overload principle of training states that training load (TL) must be sufficient to threaten the homeostasis of cells, tissues, organs, and/or body. However, there is no "golden standard" for TL measurement. The aim of this study was to examine if any post-exercise heart rate variability (HRV) indices could be used to evaluate TL in exercises with different intensities and durations. Thirteen endurance-trained males (35 +/- 5 year) performed MODE (moderate intensity, 3 km at 60% of the maximal velocity of the graded maximal test (vVO(2max))), HI (high intensity, 3 km at 85% vVO(2max)), and PRO (prolonged, 14 km at 60% vVO(2max)) exercises on a treadmill. HRV was analyzed with short-time Fourier-transform method during rest, exercise, and 15-min recovery. Rating of perceived exertion (RPE), blood lactate (BLa), and HFP(120) (mean of 0-120 s post-exercise) described TL of these exercises similarly, being different for HI (P < 0.05) and PRO (P < 0.05) when compared with MODE. RPE and BLa also correlated negatively with HFP(120) (r = -0.604, -0.401), LFP(120) (-0.634, -0.601), and TP(120) (-0.691, -0.569). HRV recovery dynamics were similar after each exercise, but the level of HRV was lower after HI than MODE. Increased intensity or duration of exercise decreased immediate HRV recovery, suggesting that post-exercise HRV may enable an objective evaluation of TL in field conditions. The first 2-min recovery seems to give enough information on HRV recovery for evaluating TL.

Heart rate variability dynamics during early recovery after different endurance exercises.

Since heart rate variability (HRV) during the first minutes of the recovery after exercise has barely been studied, we wanted to find out HRV dynamics immediately after five different constant-speed exercises. Thirteen sedentary women performed two low-intensity (3,500 m [3,500(LI)] and 7,000 m [7,000(LI)] at 50% of the velocity of VO(2max) [vVO(2max)]), two moderate-intensity (3,500 m [3,500(MI)] and 7,000 m [7,000(MI)] at approximately 63% vVO(2max)) and one high-intensity (3,500 m at approximately 74% vVO(2max) [3,500(HI)]) exercises on a treadmill. HRV was analyzed with short-time Fourier transform method during the 30-min recovery. High frequency power (HFP) was for the first time higher than at the end of the exercise after the first minute of the recovery (3,500(LI) and 7,000(LI), P < 0.001), after the fourth (3,500(MI), P < 0.05) and the fifth (7,000(MI), P < 0.05) minute of the recovery and at the end of the 30-min recovery (3,500(HI), P < 0.01). There were no differences in HRV between 3,500(LI) and 7,000(LI) or between 3,500(MI) and 7,000(MI) during the recovery. The levels of HFP and TP were higher during the whole recovery after 3,500(LI) compared to 3,500(MI) and 3,500(HI). We found increased HFP, presumably caused by vagal reactivation, during the first 5 min of the recovery after each exercise, except for 3,500(HI). The increased intensity of the exercise resulted in slower recovery of HFP as well as lower levels of HFP and TP when compared to low-intensity exercise. Instead, the doubled running distance had no influence on HRV recovery.