Sex differences in muscle pain: self-care behaviors and effects on daily activities

Delayed-Onset Muscle Soreness Alters Mechanical Sensitivity, but Not Thermal Sensitivity or Pain Modulatory Function

Introduction

Many clinical musculoskeletal pain conditions are characterized by chronic inflammation that sensitizes nociceptors. An unresolved issue is whether inflammation affects all nociceptors in a similar manner. Exercise-induced muscle damage (EIMD) has been proposed as a model for simulating clinical inflammatory pain in healthy samples. We sought to test the effect of EIMD on various painful stimuli (pressure and thermal), central pain processing (via the nociceptive flexion reflex) and endogenous pain modulation via conditioned pain modulation and exercise-induced hypoalgesia.

Methods

Eighteen participants (9F, age: 24.6 ± 3.3) were recruited for repeated measures testing and each completed pain sensitivity testing prior to and 48 hours after an eccentric exercise protocol. The participants performed a minimum of 6 rounds of 10 eccentric knee extension exercises to induce muscle damage and localized inflammation in the right quadriceps. Force decrements, knee range-of-motion, and delayed onset muscle soreness (DOMS) were used to quantify EIMD.

Results

There was a significant main effect of time for pressure pain (%diff; -58.9 ± 23.1; p = 0.02, ηp2 = 0.28) but no significant main effect was observed for limb (%diff; -15.5 ± 23.9; p = 0.53, ηp2 = 0.02). In contrast, there was a significant interaction between time and limb (p < 0.001, ηp2 = 0.47) whereby participants had lower pressure pain sensitivity in the right leg only after the damage protocol (%diff; -105.9 ± 29.2; p = 0.002).

Discussion

Individuals with chronic inflammatory pain usually have an increased sensitivity to pressure, thermal, and electrical stimuli, however, our sample, following muscle damage to induce acute inflammation only had sensitivity to mechanical pain. Exercise induced inflammation may reflect a peripheral sensitivity localized to the damaged muscle rather than a global sensitivity like those with chronic pain display.

Neural and Psychosocial Mechanisms Underlying Alcohol Use and Pain Interactions: Overview of Current Evidence and Future Directions

Purpose of Review

A growing body of research indicates bidirectional associations between alcohol use and pain. In this review, we highlight common neural and psychosocial mechanisms underlying pain and alcohol use and identify current gaps in the literature regarding alcohol/pain interactions. We also suggest future directions for the field moving forward, including more nuanced conceptualization of alcohol's negative reinforcing effects in the context of pain, broader use of clinically-relevant experimental pain induction modalities, and characterization of age, biological sex, gender, race, and ethnicity as moderators of pain/alcohol interactions.

Recent Findings

Acute alcohol intake has analgesic and negative-reinforcing effects in the context of pain, and chronic heavy alcohol use appears to increase risk for development of chronic pain. At the same time, pain, both acute and chronic, acts as a proximal antecedent for alcohol use and is associated with relapse risk for individuals in recovery from alcohol use disorder.

Summary

Although the links between alcohol use and pain are increasingly appreciated, significant gaps in understanding remain and systematic study of alcohol/pain interactions at all levels, including basic, preclinical, translational, and interventional, is needed.

Validation of CARE Scale-7 in treatment-seeking patients with chronic pain: measurement of sex invariance

Supplemental Digital Content is Available in the Text.

The CARE Scale-7 is the first validated instrument to assess self-care difficulty in both sexes and may promote individualized care planning among chronic pain patients.

Objectives:

Social and interpersonal factors impact the trajectory of chronic pain. We previously developed and validated a 2-factor, 7-item measure to assess interpersonal factors, including relationship guilt and worry and difficulty prioritizing self-care in chronic pain. Here, we confirm the factor structure and examine the sex invariance of the two-factor structure of the CARE Scale-7.

Methods:

Data were collected as part of routine clinical care at a tertiary pain clinic using the Collaborative Health Outcomes Information Registry. Patient participants (67% women) were predominantly middle-aged (M = 50.9 years, SD = 17.8), married (55.2%), and White/non-Hispanic (55.7%). Data included demographics, pain characteristics, CARE Scale-7, pain catastrophizing, and Patient-Reported Outcomes Measurement Information System psychological and physical function measures. Confirmatory factor analysis was conducted to validate the factor structure of the CARE Scale, and a stepwise approach to measurement invariances by sex examined configural, metric, and scalar invariance.

Results:

Internal consistency of the scale items ensured suitability for factor analyses. Confirmatory factor analysis findings revealed an overall good fit of the 2-factor model among males and females and that CARE Scale-7 is in fact sex invariant. Finally, CARE Scale-7 showed convergent validity with pain-related outcomes.

Discussion:

The CARE Scale is the first validated instrument to assess self-care in both sexes among patients with chronic pain. The subscale of difficulty prioritizing self-care emerged as a potentially unique factor that should be integrated in clinical assessment. CARE Scale may facilitate standardized measurement in research and clinical contexts, which may inform a comprehensive treatment focus that integrates individualized self-care planning.

Nutritional and Pharmacological Interventions to Expedite Recovery Following Muscle-Damaging Exercise in Older Adults: A Narrative Review of the Literature

Exercise-induced muscle damage (EIMD) manifests as muscle soreness, inflammation, and reductions in force generating capacity that can last for several days after exercise. The ability to recover and repair damaged tissues following EIMD is impaired with age, with older adults (≥50 years old) experiencing a slower rate of recovery than their younger counterparts do for the equivalent exercise bout. This narrative review discusses the literature examining the effect of nutritional or pharmacological supplements taken to counter the potentially debilitating effects of EIMD in older adults. Studies have assessed the effects of nonsteroidal anti-inflammatory drugs, vitamin C and/or E, or higher protein diets on recovery in older adults. Each intervention showed some promise for attenuating EIMD, but, overall, there is a paucity of available data in this population, and more studies are required to determine the influence of nutrition or pharmacological interventions on EIMD in older adults.

Pre-Bed Casein Protein Supplementation Does Not Enhance Acute Functional Recovery in Physically Active Males and Females When Exercise is Performed in the Morning

This study examined whether consuming casein protein (CP) pre-sleep could accelerate acute recovery following muscle-damaging exercise. Thirty-nine active males and females performed 100 drop jumps in the morning, consumed their habitual diet during the day, and then within 30 min pre-bed consumed either ~40 g of CP (n = 19) or ~40 g of a carbohydrate-only control (CON) (n = 20). Maximal isometric voluntary contractions (MIVC), countermovement jumps (CMJ), pressure-pain threshold (PPT), subjective muscle soreness and the brief assessment of mood adapted (BAM+) were measured pre, 24 and 48 h following the drop jumps. MIVC decreased in CP and CON post-exercise, peaking at 24 h post (CP: -8.5 ± 3.5 vs. CON: -13.0 ± 2.9%, respectively); however, no between-group differences were observed (p = 0.486; η_p² =0.02). There were also no group differences in the recovery of CMJ height, PPT and BAM+ (p > 0.05). Subjective muscle soreness increased post-exercise, but no group differences were present at 24 h (CP: 92 ± 31 mm vs. CON: 90 ± 46 mm) or 48 h (CP: 90 ± 44 mm vs. CON: 80 ± 58 mm) (p > 0.05). These data suggest that pre-bed supplementation with ~40 g of CP is no more beneficial than CON for accelerating the recovery following muscle-damaging exercise.

Gender differences in residual effect of prior drop jumps on oxygen uptake during heavy cycling exercise

BACKGROUND AND OBJECTIVE

Unaccustomed eccentric or eccentric-concentric exercise leaves us stiff and sore the next day and can cause muscle damage. The data about the residual effect of prior eccentric-concentric exercises on oxygen uptake (VO₂) during constant cycling exercise in women or the data about differences of such effect between genders are scarce. Therefore, the aim of this study was to assess differences of the residual effect of PDJ on VO₂ during HCE and indirect muscle damage parameters between women and men.

MATERIALS AND METHODS

The study aimed to asses differences of the residual effect of prior drop jumps (PDJ) on VO₂ during heavy cycling exercise (HCE) and indirect muscle damage parameters between men (n=8) and women (n=11). On four different days participants performed one incremental cycling exercise and three HCE (control [CON], 45min [45' PDJ] and 24h [24h PDJ] after 100 drop jumps). The intensity of HCE was set to work rate corresponding to 50% of the difference between the second and the first ventilatory thresholds which were determined analyzing pulmonary gas exchange parameters during incremental cycling exercise. Capillary blood samples were collected in order to measure blood lactate concentration immediately after HCE and serum creatine kinase (CK) activity 24h after PDJ. Subjects rated perceived exertion and delayed onset muscle soreness (DOMS) using 20 and 10 point scales, respectively.

RESULTS

VO₂ at 3-6min of HCE performed 45' after PDJ was significantly increased as compared to CON HCE only in the male group. Both men and women felt moderate muscle pain. CK activity was significantly increased 24h after PDJ in the male group. Both during HCE 45' PDJ and 24h PDJ, the significant positive correlation was observed between relative changes of VO₂ during steady state of HCE and CK activity only in the male group.

CONCLUSIONS

Prior eccentric-concentric exercise of thigh muscles (100 drop jumps) accelerates VO₂ kinetics at the start and increases VO₂ during steady state of heavy cycling only in the male group. So, prior exercise of such type has a higher negative impact on cycling economy in men than in women and this might be related to greater muscle damage and fatigue in physically active male persons after plyometric exercise.

Distúrbios musculoesqueléticos em extremidades superiores distais entre homens e mulheres: resultados de estudo na indústria

Resumo Objetivo: estudar a associação entre distúrbios musculoesqueléticos em extremidades superiores distais (DMED) e a variável sexo na indústria de plástico. Método: estudo transversal com 577 trabalhadores. O DMED foi definido pela presença de dor nos últimos doze meses, com duração maior que uma semana ou frequência mensal, causando restrição ao trabalho ou busca por assistência médica, ou gravidade ≥ 3 (de 0 a 5), em pelo menos uma das regiões: dedos, punhos, mãos, antebraços e cotovelos. Covariáveis de interesse foram demandas físicas e psicossociais no trabalho, variáveis sociodemográficas e de estilo de vida, condicionamento físico e trabalho doméstico. Regressão logística múltipla analisou interação estatística e confundimento. Resultados: a ocorrência de DMED foi maior entre as mulheres, de forma independente das demandas ocupacionais e extralaborais testadas. Condicionamento físico foi variável de interação e demandas psicossociais, confundidora. Homens que referiram bom condicionamento físico apresentaram prevalência menor do que aqueles com mau condicionamento. Nas mulheres, estar bem condicionada fisicamente foi insuficiente para alterar substancialmente sua alta morbidade musculoesquelética. Conclusão: diferenças na exposição ocupacional são insuficientes para explicar a maior morbidade em mulheres. É necessário considerar a diversidade entre os sexos, seja socialmente determinada ou relativa à natureza biomecânica do corpo, com diferentes respostas frente às demandas do trabalho.

Whole-Body Vibration While Squatting and Delayed-Onset Muscle Soreness in Women

CONTEXT

Research into alleviating muscle pain and symptoms in individuals after delayed-onset muscle soreness (DOMS) has been inconsistent and unsuccessful in demonstrating a useful recovery modality.

OBJECTIVE

To investigate the effects of short-term whole-body vibration (WBV) on DOMS over a 72-hour period after a high-intensity exercise protocol.

DESIGN

Randomized controlled clinical trial.

SETTING

University laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty women volunteered to participate in 4 testing sessions and were assigned randomly to a WBV group (n = 16; age = 21.0 ± 1.9 years, height = 164.86 ± 6.73 cm, mass = 58.58 ± 9.32 kg) or a control group (n = 14; age = 22.00 ± 1.97 years, height = 166.65 ± 8.04 cm, mass = 58.69 ± 12.92 kg).

INTERVENTION(S)

Participants performed 4 sets to failure of single-legged split squats with 40% of their body weight to induce muscle soreness in the quadriceps. The WBV or control treatment was administered each day after DOMS.

MAIN OUTCOME MEASURE(S)

Unilateral pressure-pain threshold (PPT), range of motion (ROM), thigh circumference, and muscle-pain ratings of the quadriceps were collected before and for 3 days after high-intensity exercise. Each day, we collected 3 sets of measures, consisting of 1 measure before the WBV or control treatment protocol (pretreatment) and 2 sets of posttreatment measures.

RESULTS

We observed no interactions for PPT, thigh circumference, and muscle pain (P > .05). An interaction was found for active ROM (P = .01), with the baseline pretreatment measure greater than the measures at baseline posttreatment 1 through 48 hours posttreatment 2 in the WBV group. For PPT, a main effect for time was revealed (P < .05), with the measure at baseline pretreatment greater than at 24 hours pretreatment and all other time points for the vastus medialis, greater than 24 hours pretreatment through 48 hours posttreatment 2 for the vastus lateralis, and greater than 24 hours pretreatment and 48 hours pretreatment for the rectus femoris. For dynamic muscle pain, we observed a main effect for time (P < .001), with the baseline pretreatment measure less than the measures at all other time points. No main effect for time was noted for thigh circumference (P = .24). No main effect for group was found for any variable (P > .05).

CONCLUSIONS

The WBV treatment approach studied did not aid in alleviating DOMS after high-intensity exercise. Further research is needed in various populations.

The effect of milk on the attenuation of exercise-induced muscle damage in males and females

PURPOSE

The consumption of 500 ml milk following muscle damaging exercise can attenuate decreases in muscle functional capacity and increases in markers of muscle damage and soreness in males. There has been no similar research in female participants. Therefore, the aim of this study was to investigate the effects of milk consumption on exercise-induced muscle damage (EIMD) in males and females.

METHODS

Thirty-two team sport players (male n = 16; female n = 16) were randomly, but equally divided into four groups: male milk, male carbohydrate, female milk, and female carbohydrate. Immediately following muscle damaging exercise, participants consumed either 500 ml of milk or 500 ml of an energy-matched carbohydrate solution. Skeletal troponin I (sTnI), creatine kinase (CK), peak torque, counter movement jump height, 20 m sprint performance and passive and active soreness were recorded prior to and 24, 48 and 72 h post-EIMD.

RESULTS

For females, milk had a likely/very likely beneficial effect on attenuating losses in peak torque at 60°/s from baseline to 24, 48 and 72 h, and a likely beneficial effect in minimising decrements in sprint performance and soreness over 72 h. Milk was unlikely to have a negative effect on serum markers of damage from baseline to 48 and 72 h. For males, milk had an unclear effect on muscle function variables. Milk had a most likely/likely beneficial effect on limiting muscle soreness from baseline to 72 h, and a possible beneficial effect on attenuating increases in CK. The effect on sTnI was unlikely to be negative from baseline-72 h. Overall gender comparisons provided many unclear outcomes. However, female participants demonstrated smaller increases in sprint time, passive soreness, active soreness (non-dominant leg) and sTnI values.

CONCLUSION

Consumption of 500 ml of milk post-EIMD can limit decrements in muscle function in females, and limit increases in soreness and serum markers of muscle damage in females and males.

Prior eccentric exercise augments muscle pain and perception of effort during cycling exercise

OBJECTIVES

This study examined the effects of exercise-induced muscle damage (EIMD) on the physiological and perceptual responses to 30 minutes of submaximal cycling at 60% of oxygen consumption (VO2 peak).

METHODS

Ten participants completed two 30-minute bouts of cycling, one before and one 48 hours after performance of strenuous (24 contractions with 120% of concentric 1-repeition maximum) eccentric exercise.

RESULTS

Eccentric exercise resulted in a significant delayed-onset muscle pain (1.6±1.6 mm to 44.8±20 mm on a 100-mm visual analog scale; P<0.001) and a 15% (P<0.001) reduction in maximal strength 48 hours after exercise. Ratings of quadriceps muscle pain (1.99±0.42 vs. 3.30±0.56; P=0.003) and perceived exertion (RPE; 13.0±0.30 vs. 13.8±0.61; P=0.02) were elevated during cycling after EIMD at identical work rates. No changes were observed in VO2 (29.6±4.6 vs. 30.2±4.4 mL/kg/min; P=0.41), heart rate (154±15 vs. 155±9 beats/min; P=0.58), and ventilation (57.2±12.1 vs. 59.8±12.7 L/min; P=0.13) during exercise after EIMD. The mean change in RPE was significantly correlated (r=0.56; P<0.01) with the change in muscle pain during cycling and delayed-onset pain during resistance exercise (r=0.86; P<0.01), but did not correlate with changes in VO2, heart rate, ventilation, and maximal strength.

DISCUSSION

These findings indicate the elevations in RPE after EIMD are likely a consequence of the EIMD with the most likely explanation being an increase in localized pain before and during cycling exercise.

Stability of conditioned pain modulation in two musculoskeletal pain models: investigating the influence of shoulder pain intensity and gender

Background

Several chronic pain populations have demonstrated decreased conditioned pain modulation (CPM). However there is still a need to investigate the stability of CPM paradigms before the measure can be recommended for implementation. The purpose of the present study was to assess whether shoulder pain intensity and gender influence CPM stability within and between sessions.

Methods

This study examined two different musculoskeletal pain models, clinical shoulder pain and an experimental model of shoulder pain induced with eccentric exercise in healthy participants. Patients in the clinical cohort (N = 134) were tested before surgery and reassessed 3 months post-surgery. The healthy cohort (N = 190) was examined before inducing pain at the shoulder, and 48 and 96 hours later.

Results

Our results provide evidence that 1) stability of inhibition is not related to changes in pain intensity, and 2) there are sex differences for CPM stability within and between days.

Conclusions

Fluctuation of pain intensity did not significantly influence CPM stability. Overall, the more stable situations for CPM were females from the clinical cohort and males from the healthy cohort.

Sex differences in exercise-induced muscle pain and muscle damage

There is uncertainty about sex differences in exercise-induced muscle pain and muscle damage due to several methodological weaknesses in the literature. This investigation tested the hypothesis that higher levels of exercise-induced muscle pain and muscle damage indicators would be found in women than men when several methodological improvements were executed in the same study. Participants (N = 33; 42% women) with an average age of 23 years (SD = 2.82) consented to participate. After a familiarization session, participants visited the laboratory before and across 4 days after eccentric exercise was completed to induce arm muscle pain and muscle damage. Our primary outcomes were arm pain ratings and pressure pain thresholds. However, we also measured the following indicators of muscle damage: arm girth; resting elbow extension; isometric elbow flexor strength; myoglobin (Mb); tumor necrosis factor (TNFa); interleukin 1beta (IL1b); and total nitric oxide (NO). Temporary induction of muscle damage was indicated by changes in all outcome measures except TNFa and IL1b. In contrast to our hypotheses, women reported moderately lower and less frequent muscle pain than men. Also, women's arm girth and Mb levels increased moderately less than men's, but the differences were not significant. Few large sex differences were detected.

PERSPECTIVE

Lower muscle pain among women than men was detected with corresponding, but nonsignificant sex differences in other muscle damage indicators. Methodological advances may have improved alignment of these results with the nonhuman animal findings. This line of research continues to show exceptions to the generalization that women experience greater pain than men.

Are there gender differences in quality of life and symptomatology between fibromyalgia patients?

The purpose of this study is to examine gender differences in quality of life (QoL) and symptomatology in fibromyalgia (FM) patients. A total of 20 men (48.0 ± 8.0 years) and 78 women (49.8 ± 7.2 years) with FM participated in the study (age range 31-63 years). Health-related QoL and FM impact were assessed by means of the Spanish versions of the Short-Form-36 Health Survey (SF36) and the Fibromyalgia Impact Questionnaire (FIQ), respectively. Comparisons in QoL were performed using one-way analysis of covariance adjusted by age and body mass index (BMI), and comparisons in FIQ dimensions were performed using Mann-Whitney test. Overall FM impact, as measured by FIQ-total score (p = .01) and FIQ-physical impairment (p = .02) was higher in men, whereas women presented higher values of FIQ-fatigue and FIQ-morning tiredness (p = .04) and less SF36-vitality (p = .02). Therefore, women appear to feel more fatigue, whereas men present higher FM overall impact. Due to the small number of men included in this study and the consequent small statistical power, these results should be taken as preliminary. Higher powered studies are warranted to further address gender differences in FM in order to design more successful treatments.

Pain-related fear and catastrophizing predict pain intensity and disability independently using an induced muscle injury model

Timing of assessment of psychological construct is controversial and results differ based on the model of pain induction. Previous studies have not used an exercise-induced injury model to investigate timing of psychological assessment. Exercise-induced injury models may be appropriate for these investigations because they approximate clinical pain conditions better than other experimental stimuli. In this study we examined the changes of psychological constructs over time and determined whether timing of assessment affected the construct's association with reports of pain intensity and disability. One-hundred twenty-six healthy volunteers completed the Fear of Pain Questionnaire (FPQ-III), Pain Catastrophizing Scale (PCS), and Tampa Scale of Kinesiophobia (TSK) prior to inducing muscle injury to the shoulder. The PCS and TSK were measured again 48 and 96 hours postinjury induction. Pain intensity and disability were collected at 48 and 96 hours and served as dependent variables in separate regression models. Results indicated that the FPQ-III had the strongest prediction of pain intensity from baseline to 96 hours. After baseline the PCS and TSK were stronger predictors of pain intensity and disability, respectively. These data provide support for the use of psychological constructs in predicting outcomes from shoulder pain. However, they deviate from the current theoretical model indicating that fear of pain is a consequence of injury and instead suggests that fear of pain before injury may influence reports of pain intensity.

PERSPECTIVE

The current study provides evidence that fear of pain can be assessed prior to injury. Furthermore, it supports that after injury pain catastrophizing and kinesiophobia are independently associated with pain and disability. Overall these data suggest that timing of psychological assessment may be an important consideration in clinical environments.

A systematic literature review of 10 years of research on sex/gender and experimental pain perception - part 1: are there really differences between women and men?

The purpose of this systematic review was to summarize and critically appraise the results of 10 years of human laboratory research on pain and sex/gender. An electronic search strategy was designed by a medical librarian and conducted in multiple databases. A total of 172 articles published between 1998 and 2008 were retrieved, analyzed, and synthesized. The first set of results (122 articles), which is presented in this paper, examined sex difference in the perception of laboratory-induced thermal, pressure, ischemic, muscle, electrical, chemical, and visceral pain in healthy subjects. This review suggests that females (F) and males (M) have comparable thresholds for cold and ischemic pain, while pressure pain thresholds are lower in F than M. There is strong evidence that F tolerate less thermal (heat, cold) and pressure pain than M but it is not the case for tolerance to ischemic pain, which is comparable in both sexes. The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities. In summary, 10 years of laboratory research have not been successful in producing a clear and consistent pattern of sex differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain. Whether laboratory studies in healthy subjects are the best paradigm to investigate sex differences in pain perception is open to question and should be discussed with a view to enhancing the clinical relevance of these experiments and developing new research avenues.

Pressure and activity-related allodynia in delayed-onset muscle pain

OBJECTIVES

Muscle pain from different activities was tested with the muscle pain expected to vary in ways that may clarify mechanisms of activity-induced exacerbation of myofascial pain.

METHODS

Participants [N=20; 45% women; 23 y old (SD=2.09)] consented to participate in a 6 session protocol. Bilateral muscle pain ratings and pressure pain thresholds (PPTs) were collected before and for 4 days after lengthening (ie, eccentric) muscle contractions were completed with the nondominant elbow flexors to induce delayed-onset muscle pain. The muscle pain ratings were collected with the arms in several conditions (eg, resting, moving, and contracting in a static position) and PPTs were collected with the arms.

RESULTS

In the ipsilateral arm, muscle pain ratings at rest and during activity significantly increased whereas PPTs significantly decreased after the eccentrics (ηs=0.17 to 0.54). The greatest increases in pain occurred during arm extension without applied load, in which there was more stretching but less force than isometrics. In the contralateral arm, neither muscle pain nor PPTs changed from baseline.

DISCUSSION

These results resemble earlier electrophysiology studies showing differential sensitization across stimuli and support that increased depth of information about aggravating activities from clinical patients is needed.

Self-reported pain and disability outcomes from an endogenous model of muscular back pain

Background

Our purpose was to develop an induced musculoskeletal pain model of acute low back pain and examine the relationship among pain, disability and fear in this model.

Methods

Delayed onset muscle soreness was induced in 52 healthy volunteers (23 women, 17 men; average age 22.4 years; average BMI 24.3) using fatiguing trunk extension exercise. Measures of pain intensity, unpleasantness, and location, and disability, were tracked for one week after exercise.

Results

Pain intensity ranged from 0 to 68 with 57.5% of participants reporting peak pain at 24 hours and 32.5% reporting this at 48 hours. The majority of participants reported pain in the low back with 33% also reporting pain in the legs. The ratio of unpleasantness to intensity indicated that the sensation was considered more unpleasant than intense. Statistical differences were noted in levels of reported disability between participants with and without leg pain.

Pain intensity at 24 hours was correlated with pain unpleasantness, pain area and disability. Also, fear of pain was associated with pain intensity and unpleasantness. Disability was predicted by sex, presence of leg pain, and pain intensity; however, the largest amount of variance was explained by pain intensity (27% of a total 40%). The second model, predicting pain intensity only included fear of pain and explained less than 10% of the variance in pain intensity.

Conclusions

Our results demonstrate a significant association between pain and disability in this model in young adults. However, the model is most applicable to patients with lower levels of pain and disability. Future work should include older adults to improve the external validity of this model.