Exercise Interventions for Preventing and Treating Low Bone Mass in the Forearm: A Systematic Review and Meta-analysis.

OBJECTIVE: To examine the effectiveness of exercises for improving forearm bone mass. DATA SOURCES: MEDLINE, EMBASE, CINAHL, AMED, Web of Science, and Cochrane CENTRAL were searched from their inception until December 2018. STUDY SELECTION: Eligibility included adults undertaking upper limb exercise interventions (≥12wk) to improve bone mass. DATA EXTRACTION: Screening of titles, abstracts, and full texts and data extraction were undertaken independently by pairs of reviewers. Included studies were quality appraised using Cochrane risk of bias tool. DATA SYNTHESIS: Exercise interventions were classified into "resistance training" of high or low intensity (HIRT/LIRT, respectively) or "impact." Random-effects meta-analysis of the percentage change in forearm bone mass from baseline was conducted. Twenty-six studies were included in the review, of which 21 provided suitable data for meta-analysis. Methodological quality ranged from "low" to "unclear" risk of bias. Exercise generally led to increases (moderate-quality evidence) in forearm bone mass (standard mean difference [SMD], 1.27; 95% CI, 0.66-1.88; overall effect Z value=4.10; P<.001). HIRT (SMD, 1.00; 95% CI, 0.37-1.62; Z value=3.11; P=.002), and LIRT (SMD, 2.36; 95% CI, 0.37-4.36; Z value=2.33; P<.001) led to moderate increases in forearm bone mass. Improvements resulting from impact exercises (SMD, 1.12; 95% CI, -1.27 to 3.50; Z value=0.92; P=.36) were not statistically significant (low-quality evidence). CONCLUSIONS: There is moderate-quality evidence that exercise is effective for improving forearm bone mass. There is moderate-quality evidence that upper body resistance exercise (HIRT/LIRT) promotes forearm bone mass but low-quality evidence for impact exercise. Current evidence is equivocal regarding which exercise is most effective for improving forearm bone mass.

Heart rate-based training intensity and its impact on injury incidence among elite-level professional soccer players.

Elite-level professional soccer players are suggested to have increased physical, technical, tactical, and psychological capabilities when compared with their subelite counterparts. Ensuring these players remain at the elite level generally involves training many different bodily systems to a high intensity or level within a short duration. This study aimed to examine whether an increase in training volume at high-intensity levels was related to injury incidence, or increased the odds of sustaining an injury. Training intensity was monitored through time spent in high-intensity (T-HI) and very high-intensity (T-VHI) zones of 85-<90% and ≥90% of maximal heart rate (HRmax), and all injuries were recorded over 2 consecutive seasons. Twenty-three, elite professional male soccer players (mean ± SD age, 25.6 ± 4.6 years; stature, 181.8 ± 6.8 cm; and body mass, 79.3 ± 8.1 kg) were studied throughout the 2-years span of the investigation. The results showed a mean total injury incidence of 18.8 (95% confidence interval [CI], 14.7-22.9) injuries per 1,000 hours of exposure. Significant correlations were found between training volume at T-HI and injury incidence (r = 0.57, p = 0.005). Further analysis revealed how players achieving more time in the T-VHI zone during training increased the odds of sustaining a match injury (odds ratio = 1.87; 95% CI, 1.12-3.12, p = 0.02) but did not increase the odds of sustaining a training injury. Reducing the number of competitive match injuries among elite-level professional players may be possible if greater focus is placed on the training intensity and volume over a period of time ensuring the potential reduction of fatigue or overuse injuries. In addition, it is important to understand the optimal training load at which adaptation occurs without raising the risk of injury.

Association between depot medroxyprogesterone acetate (DMPA), physical activity and bone health.

Physical activity has been advocated for women in the hope of offsetting progestin-only contraceptive-related loss in bone mineral density. There is limited evidence for the beneficial effect of physical activity on bone health of hypo-oestrogenic premenopausal women. The aim of this cross-sectional study was to examine the relationship between physical activity and bone health [as measured by quantitative ultrasound (QUS)] of depot-medroxyprogesterone acetate (DMPA) users, and to investigate whether QUS measurements of DMPA users and non-users differed according to physical activity. Bone health of 48 DMPA users and 48 age-matched controls (22.83 ± 3.2 years) was assessed using calcaneal broadband ultrasound attenuation (BUA). Participants were categorised into low and high levels of physical activity based on their exposure to bone-loading exercise. Analysis of covariance was conducted to determine if QUS measurements of DMPA users and non-DMPA users differed within levels of bone-loading physical activity after controlling for body mass index. The duration of DMPA use ranged from 6 to 132 months. Participants' reference bone-loading exposure time averaged 3.3 ± 1.8 years. Data analysis revealed that DMPA users had significantly lower BUA by 6.54 dB/MHz (t (95) = -2.411, p = 0.018) compared to non-users of DMPA. Concurrently high levels of physical activity and DMPA use led to 1.996 dB/MHz decreases in BUA. A cycle of prolonged DMPA use and concurrent engagement in high levels of physical activity appears detrimental to bone health. It is suggested that the lack of oestrogen may counteract the effects of physical activity by inhibiting bone formation in response to mechanical bone-loading.

Menopause Osteoporosis and Bone Intervention Using Lifestyle Exercise: A Randomized Controlled Study.

Background: The aim of the study was to examine the feasibility for postmenopausal women of a bone-strengthening jumping intervention, which has been previously successful for premenopausal women. Materials and Methods: Forty-nine participants (mean ± standard deviation [SD] age = 57.8 ± 4.3 years) were randomized into either an exercise intervention or sham-control group in a double-blinded fashion. The intervention consisted of 10 maximal, rest-inserted countermovement jumps, performed three times a week on a hard surface without shoes for 8 months. Sham-control participants performed unilateral balance exercises of equivalent duration. Results: The jumps were well tolerated, with women in the jumping group completing 95% of the prescribed exercise. Of the participants who completed the study (n = 23 intervention, n = 16 control), there were no significant differences in broadband ultrasound attenuation (BUA) using quantitative ultrasound (QUS) of the calcaneum within and between groups (mean ± SD BUA = 64.9 ± 7.3 and 66.6 ± 6.5 dB/MHz for intervention pre- and post-trial, respectively, versus mean ± SD BUA = 63.6 ± 4.2 and 64.4 ± 4.5 dB/MHz for sham-controls pre- and post-trial, respectively) or for any QUS parameters, although there was a 3% increase in BUA for intervention participants. Conclusions: Recruitment and participation rates were feasible for this duration of study and the exercise was acceptable. For a future study of this nature, 48 participants would be required to ensure adequate power, especially as lifestyle variations and post-menopausal hypoestrogenism prevent substantial gains in bone strength with high-impact exercise.

The combined effect of time of day and menstrual cycle on lactate threshold.

PURPOSE: This study examined the isolated and combined effects of time of day and menstrual cycle phase on the determination of the lactate threshold (Tlac) and blood lactate concentration. METHODS: Eleven endurance-trained female athletes (mean age 32.4+/- 6.9 yr) were tested at 06:00 and 18:00 h and at two phases of the menstrual cycle, the midfollicular phase and the midluteal phase. Capillary blood (25 muL) was obtained from the tip of the toe at rest, and during the last 30 s of a continuous, multistage, 3-min incremental protocol on the Concept II rowing ergometer. To determine Tlac, a curve-fitting procedure (Dmax method), a visual method (Tlac-vis), and the fixed blood lactate concentration of 4.0 mmol.L (Tlac-4 mM) were used. Ventilatory threshold (Tvent) was also determined. RESULTS: In the midluteal phase of the menstrual cycle, Tlac-4 mM occurred at a significantly higher exercise intensity, heart rate, and oxygen consumption than it did in the midfollicular phase. Blood lactate concentration at Tvent and at Tlac using the Dmax method was significantly lower in the midluteal phase. No significant interaction effects (menstrual cycle x time of day) were observed for any of the methods used to determine Tlac or for values of blood lactate concentration at rest and at maximum. CONCLUSION: These findings suggest that, when using fixed values of blood lactate in physiologic assessment, consideration should be given to the menstrual cycle phase in which the test is carried out.

Toe and earlobe capillary blood sampling for lactate threshold determination in rowing.

PURPOSE: In rowing ergometry, blood for determining lactate concentration can be removed from the toe tip without the rower having to stop. The purpose of the study was to examine whether sampling blood from the toe versus the earlobe would affect lactate threshold (Tlac) determination. METHODS: Ten physically active males (mean ± age 21.2 ± 2.3 y; stature 179.2 ± 7.5 cm; body mass 81.7 ± 12.7 kg) completed a multistage, 3 min incremental protocol on the Concept II rowing ergometer. Blood was sampled simultaneously from the toe tip and earlobe between stages. Three different methods were used to determine Tlac. RESULTS: There were wider variations due to the method of Tlac determination than due to the sample site; for example, ANOVA results for power output were F(1.25, 11.25) = 11.385, P = .004 for method and F(1, 9) = 0.633, P = .45 for site. The greatest differences in Tlac due to sample site in rowing occurred when Tlac was determined using an increase in blood lactate concentration by >1 mmol/L from baseline (TlacΔ1). CONCLUSIONS: The toe tip can be used as a suitable sample site for blood collection during rowing ergometry, but caution is needed when using the earlobe and toe tip interchangeably to prescribe training intensities based on Tlac, especially when using TlacΔ1 or at lower concentrations of lactate.