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To examine validity of TIRE scores, responses of the 283 participants to the 14 TIRE items were examined. Implausible outliers were identified (e.g., I intend to quit if I feel no pain, yet I am extremely unlikely to quit if I feel stage 2 pain), such that 27 cases were removed. Descriptive statistics and correlations of TIRE items for the remaining 256 hikers are presented in Table 4.7.

Table 4.7

Means, Standard Deviations, and Correlations of Pre-hike Test of Intention to Reduce Effort (TIRE) Items of Hikers Attempting to Hike the Appalachian Trail (n = 256)

Note. OTC = over-the-counter. Pain refers to overuse injury pain. Response scale for the first seven items is 0 - 10; response scale for the last seven items is 1 - 10. Higher scores for all items indicate a higher risk for taking an action that could contribute to overuse injury.

*p < .05. **p < .01.

Range Mean SD 1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 Amount of pain to hike slower 2 - 10 5.18 1.69 1 2 Amount of pain to rest more 1 - 10 4.99 1.58 .76** 1 3 Amount of pain to hike fewer miles 2 - 10 5.66 1.57 .81** .70** 1 4 Amount of pain to take a day off 1 - 10 7.09 1.55 .48** .51** .56** 1 5 Amount of pain to quit thru-hike 5 - 10 9.52 0.86 .26** .27** .35** .42** 1 6 Amount of pain to take OTC 0 - 10 4.77 2.18 .37** .40** .36** .42** .27** 1 7 Amount of pain to get medical help 3 - 10 8.20 1.44 .42** .43** .46** .46** .52** .43** 1 8 Hike slower due to stage 2 pain 1 - 10 5.00 2.36 .46** .45** .51** .28** .22** .23** .28** 1 9 Rest more due to stage 2 pain 1 - 10 4.91 2.34 .40** .46** .44** .31** .19** .23** .30** .86** 1 10 Hike fewer miles due to stage 2 pain 1 - 10 5.39 2.40 .45** .44** .50** .31** .21** .21** .23** .91** .82** 1 11 Take a day off due to stage 2 pain 1 - 10 6.74 2.53 .18** .23** .31** .36** .24** .14* .21** .53** .58** .58** 1 12 Quit thru-hike due to stage 2 pain 3 - 10 9.43 1.15 .10 .16* .14* .08 .33** .08 .19** .16* .13* .19** .32** 1 13 Take OTC due to stage 2 pain 1 - 10 4.08 2.80 .16* .14* .23** .17** .10 .61** .20** .45** .43** .42** .40** .08 1 14 Get medical help due to stage 2 pain 1 - 10 7.55 2.37 .17** .20** .20** .20** .22** .24** .42** .35** .35** .32** .51** .46** .37** 1

4.3.2.1 Factorial validity. The factorial validity of the TIRE was examined with an EFA. The results of the EFA are shown in Table 4.8, Figure 4.3, and Table 4.9.

Table 4.8

Factor Loadings of Pattern Matrix and Structure Matrix of the Items on the Test of Intentions to Reduce Effort (TIRE) with Direct Oblimen Rotation for Four-Factor (a), Three-Factor (b), and Two-Factor (c) Models

Note. Factor pattern and factor structure coefficients are presented (factor pattern/factor structure). Factor pattern coefficients greater than .36 are in bold type. h2 = communality coefficients. Communality coefficients less than .6 are italicized. OTC = Over-the-counter pain relievers.

a.

h2 1 2 3 4

1 Amount of pain to hike slower .77 .86/.86 -.15/-.34 -.11/.16 .01/-.26 2 Amount of pain to hike fewer miles .75 .80/.85 -.19/-.40 -.01/.27 -.01/-.31 3 Amount of pain to rest more .68 .78/.82 -.16/-.36 -.03/.23 <-.01/-.28 4 Amount of pain to take a day off .45 .55/.63 .01/-.21 .17/.36 -.13/-.34 5 Amount of pain to get medical help .51 .43/.57 .12/-.15 .40/.54 -.18/-.39 6 Hike fewer miles due to stage 2 pain .88 .18/.43 -.87/-.92 .02/.28 <-.01/-.35 7 Hike slower due to stage 2 pain .89 .19/.41 -.86/-.92 -.01/.30 -.04/-.31 8 Rest more due to stage 2 pain .79 .16/.39 -.80/-.87 .03/.30 -.07/-.35 9 Take a day off due to stage 2 pain .55 -.06/.21 -.51/-.62 .41/.54 -.07/-.31 10 Get medical help due to stage 2 pain .54 -.10/.17 -.18/-.36 .62/.69 -.17/-.36 11 Quit thru-hike due to stage 2 pain .35 -.03/.12 -.04/-.16 .61/.58 .09/-.08 12 Amount of pain to quit thru-hike .38 -.32/.43 .10/-.11 .46/.53 -.02/-.22 13 Amount of pain to take OTC .78 .27/.47 .18/-.11 -.02/.23 -.81/-.84 14 Take OTC due to stage 2 pain .75 -.20/.12 -.29/-.46 -.01/.23 -.79/-.81

Initial Eigenvalues - 5.77 1.87 1.53 1.22 Percentage of Variance - 41.2% 13.4% 11.0% 8.7%

Factor α - .86 .91 .72 .76

b.

h2 1 2 3

7 Hike slower due to stage 2 pain .95 .94/.97 .07/.48 <.01/.34 6 Hike fewer miles due to stage 2 pain .87 .90/.93 .08/.47 -.01/.31 8 Rest more due to stage 2 pain .79 .84/.88 .06/.44 .04/.34 1 Amount of pain to hike slower .86 .02/.42 .93/.93 -.01/.27 3 Amount of pain to rest more .70 .08/.43 .79/.83 .02/.28 2 Amount of pain to hike fewer miles .73 .12/.47 .78/.85 .04/.31 13 Amount of pain to take OTC .71 -.17/.21 .26/.42 .79/.81 14 Take OTC due to stage 2 pain .74 .28/.46 -.20/.16 .78/.82 Initial Eigenvalues - 4.39 1.39 1.21 Percentage of Variance - 54.9% 17.7% 15.1%

Factor α - .95 .90 .76

c.

h2 1 2

7 Hike slower due to stage 2 pain .95 .98/.98 <.00/.54 6 Hike fewer miles due to stage 2 pain .87 .93/.93 .01/.53 8 Rest more due to stage 2 pain .78 .88/.89 <.01/.49 1 Amount of pain to hike slower .89 -.08/.47 .98/.94 2 Amount of pain to hike fewer miles .74 .05/.52 .83/.86 3 Amount of pain to rest more .67 .04/.48 .79/.82 Initial Eigenvalues - 4.00 1.25 Percentage of Variance - 66.6% 20.9%

Factor α - .95 .90

Item

Four Factor Model Item

Three Factor Model Item

a. b. c.

Figure 4.3. Scree plots produced from parallel analyses with a) 14 items, b) 8 items, and c) 6 items. The number of markers above the point where the lines intersects indicates the number of factors to be retained.

Table 4.9

Factor Correlations of Three Solutions for Items of the Test of Intentions to Reduce Effort

Note. See text for description of different factors within each model.

The first solution yielded a four-factor model. Monte Carlo parallel analysis with the 14 items and 1000 replications supported a solution of up to seven factors. The scree plot was ambiguous; inflexions supported retention of up to five factors. Based on Kaiser criteria, four factors were extracted, which explained 74.3% of the variance of behavioural intentions. Communalities averaged .65, but communalities for six items were below .60. The six items pertained to quitting, getting medical help, and taking a day off, which could be regarded as more extreme actions one might take in response to overuse pain, as opposed to, for examples, slowing down or taking an Ibuprofen.

The factor pattern coefficients were above .40. Five items loaded on the first factor, which explained 41.2% of the variance. Four of these items loaded exclusively on the first factor and appeared related to effort reduction (e.g., hike slower, take a day off) across pain levels, whilst the fifth, get medical help, did not. The second factor, explaining 13.5% of the

Factor 1 2 3 4 Factor 1 2 3 Factor 1 2

1 - 1 - 1 -

2 -.26 - 2 .44 - 2 .56 -

3 .28 -.26 - 3 .34 .29 -

4 -.31 .29 -.28 -

Three Factor Model Two Factor Model Four Factor Model

overuse pain. Five items loaded on the third factor, explaining 11.0% of the variance; three of the items loaded exclusively. The content appeared to represent more extreme actions one might take in response to overuse pain (i.e., quit, seek medical help), or taking a day off due to low-level, stage 2 pain. All five of these items had communalities below .60. Finally, the fourth factor consisted of the two intentions regarding taking over-the-counter pain relievers; the two items loaded exclusively on this factor, and explained 8.7% of the variance. As expected with the oblique rotation, there were small to moderate correlations between the factors.

To improve the clarity and psychological meaningfulness of the solution, the factor analysis was conducted again after removing all items with communalities below .6, including the two items with cross-loadings. Monte Carlo parallel analysis with the remaining 8 items and 1000 replications supported a three-factor model, as did the scree plot and Kaiser

criterion. The three factors explained 87.3% of the variance of behavioural intentions. Communalities ranged between .70 and .95, and averaged .79. The factor pattern coefficients were above .77. Three items loaded exclusively on the first factor, which explained 54.9% of the variance. All three were related to effort reduction across pain levels. The second factor, explaining 17.7% of the variance, consisted of three items loading exclusively on the factor. These three effort-reduction actions were specific to stage 2 overuse pain. The third factor consisted of the two intentions regarding taking over-the-counter pain relievers; the two items loaded exclusively on this factor, and explained 15.1% of the variance. Correlation of the two items (r = .61) was below the value for retention of two-item factors (r = .70), and therefore is considered unstable. The three factors correlated moderately, reflecting use of the oblique rotation.

Given the third factor was deemed unstable, another factor analysis was conducted after removing the two items regarding over-the-counter pain relievers. Monte Carlo parallel analysis with the remaining 6 items and 1000 replications supported a two-factor model, as did the scree plot and Kaiser criterion. The two factors explained 87.5% of the variance of behavioural intentions. Communalities ranged between .67 and .95, and averaged .82. The factor pattern coefficients were above .78. The three items, related to effort reduction actions (i.e., rest more, hike fewer miles/slower) across pain levels, loaded exclusively on the first factor, which explained 66.6% of the variance. The second factor, explaining 20.9% of the variance, consisted of the same three effort-reduction actions, but in response to Stage 2, low- level pain; the three items loaded exclusively on the factor. As expected with the oblique

In comparing the three models, KMOs values for the four-factor, three-factor, and two-factor models were .81, .80, and .81, respectively. The total variance accounted for by the 4-factor, 3-factor, and 2-factor models was 74.3%, 87.3%, and 87.5%, respectively. The internal consistencies of the four-factor, three-factor, and two-factor models were acceptable (i.e., α = .88, .88, and .89, respectively). However, the two-factor model appeared most stable across all of the factor retention analytic criteria. In addition, it demonstrated a simple,

interpretable structure: All items in the first factor encompassed effort-reduction intentions in response to low-level, stage two overuse injury pain, hereafter referred to as Factor 1. All items in the second factor encompassed effort-reduction intentions across all overuse pain levels, hereafter referred to as Factor 2. To sum up the EFA process, a two-factor solution was deemed optimal and thus was used in the current study.

4.3.2.2 Construct validity. Significant correlations of scores on measures of social identity and mental toughness with TIRE scores were considered to be indicative of construct validity. There were no significant correlations between social identification and TIRE factor scores. Correlations between scores of four social identity content items (i.e., complete thru- hike, not whining, being purist, being sensible) and one or both TIRE factors scores were significant and positive, ranging from r = .14 to r = .19. Higher mental toughness scores were significantly correlated (r = .16) with higher intentions to maintain effort despite low-level pain, as evidenced by the significant, positive correlations. Overall, the pattern of correlations provided equivocal support for the construct validity of the two-factor TIRE.

4.3.2.3 Predictive validity. Significant relationships between scores on the TIRE, administered before the hike, and severity of overuse injury that occurred during the hike were considered to be indicative of predictive validity of the TIRE. Scores on both TIRE factors significantly correlated with higher pain levels (r = .20, r = .22). The TIRE factor regarding intentions to reduce effort in response to Stage 2, low-level pain significantly differentiated Stages 2 and 3 (p = .01, d = .37). That is, those who did not intend to reduce effort if they felt low-level pain were more apt to incur functional limitation. The relationships between TIRE factors and severity outcomes indicated some support for the predictive validity of the TIRE factors.