Training volume is associated with pain sensitivity, but not with endogenous pain modulation, in competitive swimmers

Quantitative Sensory Changes Related to Physical Activity in Adult Populations: A Scoping Review

ABSTRACT

Exercise-induced hypoalgesia related to physical activity produces sensory adaptations, but its mechanism remains unclear. Quantitative sensory testing is an effective measurement tool to identify sensory changes, but the extent of evidence linking quantitative sensory testing and physical activity has not been explored. The purpose of this scoping review is to synthesize the evidence on using quantitative sensory testing to evaluate psychophysical changes related to physical activity in adult populations. The researchers developed a comprehensive search strategy with a Health Sciences Librarian using the Arksey and O'Malley Methodological framework. Four databases (Medline [PubMed], CINAHL, Web of Science, and Embase) were searched for peer-reviewed primary research. After 2790 articles were evaluated, 196 studies were included for final review. More than half of studies used randomized controlled trial design (50.5%), followed by quasi-experimental (24.0%) and observational (25.5%) strategies. Healthy adults (42.9%) and individuals with chronic health conditions (20.9%) were examined most frequently. Aerobic (27.6%) and strength (21.4%) physical activity types were most commonly studied. Static quantitative sensory testing measures of pressure pain threshold (84%) were used most frequently. The findings of this scoping review demonstrate available evidence for quantitative sensory testing as a measurement tool of neuromodulation related to physical activity in adult populations. A systematic review is warranted to examine outcomes and recommendations.

Personal influencing factors for pressure pain threshold in healthy people: A systematic review and meta-analysis

All studies that investigated personal factors influencing pressure pain threshold (PPT) in healthy people were synthesized. Data was summarized, and risk of bias (RoB) and level of evidence were determined. Results were pooled per influencing factor, grouped by body region and included in meta-analyses. Fifty-four studies were eligible. Five had low, nine moderate, and 40 high RoB. Following meta-analyses, a strong conclusion was found for the influence of scapular position, a moderate for the influence of gender, and a weak for the influence of age (shoulder/arm region) and blood pressure on PPT. In addition, body mass index, gender (leg region), alcohol consumption and pain vigilance may not influence PPT. Based on qualitative summary, depression and menopause may not influence PPT. For other variables there was only preliminary or conflicting evidence. However, caution is advised, since the majority of included studies showed a high RoB and several were not eligible to include in meta-analyses. Heterogeneity was high in the performed meta-analyses, and most conclusions were weak. More standardized research is necessary.

The Relationship Between Workload and Non-Contact Musculoskeletal Injury in College Swimmers: A Prospective Cohort Study

CONTEXT

Swimmers are known for high training loads and overuse injuries, but few studies have investigated the relationship between the two at the college level.

OBJECTIVE

To determine the association between workload and non-contact musculoskeletal injury in college swimmers. We hypothesized (1) higher overall workload (kilometers swum throughout the season) would be associated with increased odds of injury and (2) the ratio of the current week's (acute) workload divided by the current month's (chronic) workload (i.e., the acute:chronic workload ratio (ACWR)) would be more strongly associated with odds of injury than acute or chronic workloads alone.

DESIGN

Prospective cohort study.

SETTING

College natatorium.

PATIENTS OR OTHER PARTICIPANTS

Thirty-seven Division III college swimmers.

MAIN OUTCOME MEASURES

Logistic regression using generalized estimating equations was used to calculate odds ratios (OR) with 95% confidence intervals (CI) for injury relative to high workloads and high ACWRs. Injury rates for several ranges of workloads and ACWRs were also calculated.

RESULTS

Eleven participants (29.7%) sustained 12 injuries, with seven injuries occurring during the participants' winter training trip. Injury was associated with high acute workloads (OR = 27.1 [95% CI = 8.2, 89.8]) and high ACWRs (OR = 25.1 [95% CI = 7.7, 81.4]) but not high chronic workloads (OR = 2.6 [95% CI = 0.3, 20.0]) or overall workloads (OR = 1.00 [95% CI = 0.99, 1.01]). High acute workloads (>37.2 km/week) and high ACWRs (>1.56) increased injury rate from ≤1% to 15% and 14%, respectively, compared to all lower acute workloads and ACWRs.

CONCLUSIONS

College swimmers can tolerate high workloads spread out over the season. However, caution should be used when prescribing high acute workloads and high ACWRs (e.g., winter training trip) due to increased odds of injury.

Pain Processing in Elite and High-Level Athletes Compared to Non-athletes

Background

Previous studies shows that elite and high-level athletes possess consistently higher pain tolerance to ischemic and cold pain stimulation compared to recreationally active. However, the data previously obtained within this field is sparse and with low consistency.

Purpose

The aim of the present study was to examine the difference in pain perception between elite and high-level endurance athletes (cross country skiers and runners), elite soccer players and non-athletes, as well to explore the impact of psychological factors on pain processing.

Methods

Seventy one healthy volunteers (33 females and 38 males) participated in the study. Soccer players (n = 17), cross country skiers (n = 12), and long-distance runners (n = 3) formed the athlete group, with 39 non-athletes as controls. Big-five personality traits, fear of pain and Grit (perseverance and passion for long-term goals) were measured prior to induction of experimental pain. Pain threshold and intensity was induced by a PC-controlled heat thermode and measured by a computerized visual analog scale. Pain tolerance was measured by the cold pressor test (CPT).

Results

Elite and high-level athletes had increased pain tolerance, higher heat pain thresholds, and reported lower pain intensity to thermal stimulation. Endurance athletes (cross country skiers and long-distance runners) had better tolerance for cold pain compared to both soccer-players and non-athletes. Furthermore, endurance athletes reported lower pain intensity compared to non-athletes, whereas both endurance athletes and soccer players had higher heat pain thresholds compared to non-athletes. Fear of Pain was the only psychological trait that had an impact on all pain measures.

Conclusion

The present findings suggest that sports with long durations of physically intense activity, leveling aerobic capacity, are associated with increased ability to tolerate pain and that the amount of training hours has an impact on this tolerance. However, the small sample size implies that the results from this study should be interpreted with caution.

Conditioned pain modulation in elite athletes: a systematic review and meta-analysis

Background and aims Elite athletes reportedly have superior pain tolerances, but it is unclear if results extend to conditioned pain modulation (CPM). The aim of our study was to synthesize existing literature in order to determine whether CPM is increased in elite athletes compared to healthy controls. Methods A systematic review and random-effects meta-analysis was conducted. Cochrane Central Register of Controlled Trials, SPORTDiscus, PsycINFO, CINAHL, Web of Science, and PubMed were searched for English-language studies that examined CPM in adult elite athlete populations. Results Seven studies were identified; all were of poor to fair methodological quality. There was no overall difference in CPM between elite athletes and controls (Hedges g = 0.37, CI95 -0.03-0.76; p = 0.07). There was heterogeneity between studies, including one that reported significantly less CPM in elite athletes compared to controls. An exploratory meta-regression indicated that a greater number of hours trained per week was associated with higher CPM. Conclusions The overall number and quality of studies was low. Despite nominally favoring higher CPM in elite athletes, aggregate results indicate no significant difference compared to healthy controls. A possible factor explaining the high degree of variability between studies is the number of hours elite athletes spent training. Implications Based on available evidence, athletes do not have remarkable endogenous pain modulation compared to controls. High quality experimental studies are needed to address the effect of hours trained per week on CPM in athletes.