Results
Preliminary analyses
Table 1 shows the means and standard deviations for all study variables across the 14 days of
data collection. As shown, the average MET scores was 12.09 indicating the present sample was
relatively active based upon current recommendations (Powers, Dodd, & Noland, 2006). The
ARTICLE IN PRESS
P.R. Giacobbi Jr. et al. / Psychology of Sport and Exercise 8 (2007) 261–274 267
estimates of internal consistency for the PANAS were .82 and .86 for the positive and negative
affect scales, respectively. Additionally, we coded the daily events reported by the participants and
found that during days 1–10 a variety of academic sources of stress were reported as the most
difficult or challenging events of the day and included written papers, group projects, oral
presentations, examinations, and the combined demands of multiple assignments. However,
throughout the assessment period there was an increase in the number of academic examinations
reported from 0 on day 1while 52 of the 59 participants reported examinations on day 14. A closer
examination of these trends revealed that during days 1–7 the average number of exams reported
was 36.29 (SD ¼ 16.18) and during days 8 through 14 the mean was 41.00 (SD ¼ 6.43). Because
of the observed variability in the number of exams reported between these two time periods we
input dummy codes for each day of data collection which resulted in an interval scale of
increasingly higher values from day 1 to day 14 of data collection. This scale was then included as
an independent variable.
Within-person associations between exercise, threat appraisals, and affect
We began the analysis by computing unconditional growth models in order to examine linear
changes between positive affect, negative affect, threat and challenge appraisals, and exercise
behavior over the 14-day data collection period. By simultaneously computing these models using
each independent variable (cognitive appraisals of threat and challenge, exercise) from the main
analysis as the criterion variable and including day as the dependent variable we were able to
examine linear changes in the independent variables during the data collection period (Singer &
Willett, 2003). The results of this analysis showed that threat appraisals were significantly
associated with day [tð54Þ ¼ 1:77, po:08 (two-tailed)], indicating significant increases in threat
appraisals throughout the 14 day assessment period. The remaining variables (exercise behavior,
positive and negative affect, and challenge appraisals) did not exhibit significant increases during
the 14 data collection period.
The main analyses assessed independent associations between threat appraisals, challenge
appraisals, exercise behavior, and day as well as two-way interactions between all of these
variables with positive affect as the dependent variables. The second model was run with negative
affect as the dependent variable. As shown in Table 2, significant and negative associations were
observed between positive affect and the day of data collection. Additionally, the interaction
between day and appraisals of challenge was significantly associated with positive affect,
suggesting that the challenge/positive affect relationship was moderated by the day of data
ARTICLE IN PRESS
Table 1
Descriptive statistics for daily affect, appraisals of daily events, exercise, and examinations
Variable Mean SD
Positive affect 30.52 8.76
Negative affect 16.57 6.90
Threat appraisals 4.46 2.56
Exercise (METS) 12.09 13.43
Academic examinations 38.64 12.08
268 P.R. Giacobbi Jr. et al. / Psychology of Sport and Exercise 8 (2007) 261–274
collection. Based on the results of the unconditional growth curve model described above, we
chose days 1, 7, and 14 as meaningful values of the day variable (i.e., the moderator) to analyze
the simple slopes relating challenge appraisal to positive affect. Results revealed that: (a) the
challenge/positive affect relationship was significant and positive on day 7 [o ¼ :77, tð54Þ ¼ 4:16,
po:001] and day 14 [o ¼ 1:22, tð54Þ ¼ 4:32, po:001] and (b) the challenge simple slope was
significant only on days 4 through 14 of data collection. Taken together, these findings indicate
that the relationship between challenge appraisal and increased positive affect emerged primarily
during the last week of data collection, a period of increasingly frequent academic exams.
Contrary to our hypotheses the independent association between exercise and positive affect
was not significant. However, the interaction of exercise and day was significant, suggesting that
the exercise/positive affect relationship was moderated by day of data collection. Therefore, we
calculated the simple slope, with its region of significance, relating exercise behavior to positive
affect, again using days 1, 7, and 14 as meaningful conditional values of the day variable. Results
revealed that: (a) the exercise/positive affect relationship was marginally significant on day 1 of
data collection (o ¼ 2:07, tð54Þ ¼ 21:76, p ¼ :084), while significant and positive on day 14
(o ¼ :115, tð54Þ ¼ 2:31, p ¼ :025) and (b) the exercise simple slope was significant only on days 12,
13, and 14 of data collection. Therefore, our findings indicate that exercise was associated with
increased positive affect only on the final 3 days of data collection, (days in which a majority of
participants reported examinations as their most stressful academic event of the day).
ARTICLE IN PRESS
Table 2
Within subjects associations between exercise, cognitive appraisals, and positive affect
Variable Coefficient Standard error t R2 DR2 w2
Positive affect
Day 0.25 0.07 3.32** .08 .05 29.03
Threat 0.07 0.14 0.47 — — 26.41
Challenge 0.77 0.18 4.18*** .11 .03 27.00
Exercise 0.02 0.03 0.89 — — 36.70
Daythreat 0.04 0.04 0.88 — — 36.28
Daychallenge 0.07 0.03 2.10* .04 .003 20.16
Dayexercise 0.01 0.00 2.82** .06 .001 34.08
Challengeexercise 0.02 0.02 1.07 — — 30.34
Threatexercise 0.03 0.02 1.69 — — 36.26
Negative affect
Day 0.08 0.08 0.95 — — 46.65
Threat 0.77 0.14 5.42*** .22 .02 32.42
Challenge 0.08 0.12 0.66 — — 35.71
Exercise 0.03 0.03 0.89 — — 29.59
Daythreat 0.03 0.03 0.74 — — 34.74
Daychallenge 0.01 0.03 0.46 — — 39.30
Dayexercise 0.00 0.00 1.46 — — 27.80
Challengeexercise 0.01 0.00 1.01 — — 27.99
Threatexercise 0.03 0.01 2.94** .07 .01 35.99
*po.05; **po.01; ***po.001.
P.R. Giacobbi Jr. et al. / Psychology of Sport and Exercise 8 (2007) 261–274 269
Also reported in Table 2 are the effect size estimates, or R-squared values, and the DR2. These
calculations reveal the size of the association between challenge and positive affect as well as day
and positive affect were generally small (Cohen, 1988; Raudenbush & Xiao-Feng, 2001). Finally,
the results of chi-square tests to determine whether the strength of the within-subjects associations
varied across participants proved non-significant in all cases with positive affect as the dependent
variable.
The results of the model with negative affect as the dependent variable revealed that threat
appraisals were significantly related with negative affect while day and exercise were not.
Interestingly, the interaction of exercise and threat revealed a significant and positive association
with negative affect while all other interaction terms were not significant suggesting that the
exercise/negative affect relationship was moderated by threat appraisal. The simple slope and
region of significance were calculated with 1.90, 4.46, and 7.02 (M71 SD) representing
meaningful conditional values for low, average, and high threat. This analysis revealed that
exercise was significantly associated with decreased negative affect when threat appraisal was low
(o ¼ 2:06, tð54Þ ¼ 25:26, po:001), while marginally associated with increased negative affect
when threat appraisal was high (o ¼ :12, tð54Þ ¼ 1:97, p ¼ :054). Furthermore, the exercise simple
slope was significantly negative when threat appraisal was between 0 and 2.69, while significantly
positive when threat appraisal was between 7.15 and 9.00. Taken together, our results indicate
that exercise was associated with reductions in negative affect when academic stressors were
mildly threatening, while associated with increases in negative affect when stressors were highly
threatening. The effect size estimates or R-squared values were .22 for the threat/negative affect
relationship and .07 for the exercise/threat interaction.
ผลลัพธ์วิเคราะห์เบื้องต้นตารางที่ 1 แสดงวิธีและส่วนเบี่ยงเบนมาตรฐานสำหรับตัวแปรการศึกษาทั้งหมดใน 14 วันเก็บรวบรวมข้อมูล แสดง เม็ทคะแนนเฉลี่ยได้ 12.09 แสดงตัวอย่างปัจจุบันได้ค่อนข้างใช้งานตามคำแนะนำปัจจุบัน (อำนาจ Dodd, & Noland, 2006) ที่บทความในวารสารจูเนียร์ P.R. Giacobbi et al. / จิตวิทยากีฬาและออกกำลังกาย 8 (2007) 261-274 267การประเมินความสอดคล้องภายในสำหรับ PANAS ถูก.82 และ.86 ในแง่บวก และลบมีผลต่อเครื่องชั่งน้ำหนัก ตามลำดับ นอกจากนี้ เรารหัสเหตุการณ์รายวันที่รายงาน โดยผู้เรียน และพบว่า ในระหว่างวันที่ 1 – 10 แหล่งวิชาการความเครียดถูกรายงานว่า เป็นสุดยาก หรือท้าทายเหตุการณ์วัน และรวมเอกสารเป็นลายลักษณ์อักษร กลุ่มโครงการ ช่องปากงานนำเสนอ ตรวจสอบ และความต้องการรวมกำหนดหลาย อย่างไรก็ตามตลอดระยะเวลาการประเมิน มีการเพิ่มจำนวนการสอบวิชาการรายงานจาก 0 ในวัน 1while 52 ร่วม 59 รายงานสอบในวันที่ 14 ใกล้ตรวจสอบแนวโน้มเหล่านี้เปิดเผยว่า ระหว่างวันที่ 1-7 จำนวนเฉลี่ยของการสอบรายงานถูก 36.29 (SD ¼ 16.18) และในระหว่างวันที่ 8-14 ค่าเฉลี่ย 41.00 (SD ¼ 6.43) เนื่องจากความแปรผันพบจำนวนสอบรายงานระหว่างเหล่านี้รอบระยะเวลาที่สองเรารหัสสัญญาณกันขโมยสำหรับแต่ละวันของการเก็บรวบรวมข้อมูลซึ่งมีผลในการช่วงของincreasingly higher values from day 1 to day 14 of data collection. This scale was then included asan independent variable.Within-person associations between exercise, threat appraisals, and affectWe began the analysis by computing unconditional growth models in order to examine linearchanges between positive affect, negative affect, threat and challenge appraisals, and exercisebehavior over the 14-day data collection period. By simultaneously computing these models usingeach independent variable (cognitive appraisals of threat and challenge, exercise) from the mainanalysis as the criterion variable and including day as the dependent variable we were able toexamine linear changes in the independent variables during the data collection period (Singer &Willett, 2003). The results of this analysis showed that threat appraisals were significantlyassociated with day [tð54Þ ¼ 1:77, po:08 (two-tailed)], indicating significant increases in threatappraisals throughout the 14 day assessment period. The remaining variables (exercise behavior,positive and negative affect, and challenge appraisals) did not exhibit significant increases duringthe 14 data collection period.The main analyses assessed independent associations between threat appraisals, challengeappraisals, exercise behavior, and day as well as two-way interactions between all of thesevariables with positive affect as the dependent variables. The second model was run with negativeaffect as the dependent variable. As shown in Table 2, significant and negative associations wereobserved between positive affect and the day of data collection. Additionally, the interactionbetween day and appraisals of challenge was significantly associated with positive affect,suggesting that the challenge/positive affect relationship was moderated by the day of dataARTICLE IN PRESSTable 1Descriptive statistics for daily affect, appraisals of daily events, exercise, and examinationsVariable Mean SDPositive affect 30.52 8.76Negative affect 16.57 6.90Threat appraisals 4.46 2.56Exercise (METS) 12.09 13.43Academic examinations 38.64 12.08268 P.R. Giacobbi Jr. et al. / Psychology of Sport and Exercise 8 (2007) 261–274collection. Based on the results of the unconditional growth curve model described above, wechose days 1, 7, and 14 as meaningful values of the day variable (i.e., the moderator) to analyzethe simple slopes relating challenge appraisal to positive affect. Results revealed that: (a) thechallenge/positive affect relationship was significant and positive on day 7 [o ¼ :77, tð54Þ ¼ 4:16,po:001] and day 14 [o ¼ 1:22, tð54Þ ¼ 4:32, po:001] and (b) the challenge simple slope wassignificant only on days 4 through 14 of data collection. Taken together, these findings indicatethat the relationship between challenge appraisal and increased positive affect emerged primarilyduring the last week of data collection, a period of increasingly frequent academic exams.Contrary to our hypotheses the independent association between exercise and positive affectwas not significant. However, the interaction of exercise and day was significant, suggesting thatthe exercise/positive affect relationship was moderated by day of data collection. Therefore, wecalculated the simple slope, with its region of significance, relating exercise behavior to positiveaffect, again using days 1, 7, and 14 as meaningful conditional values of the day variable. Resultsrevealed that: (a) the exercise/positive affect relationship was marginally significant on day 1 ofdata collection (o ¼ 2:07, tð54Þ ¼ 21:76, p ¼ :084), while significant and positive on day 14(o ¼ :115, tð54Þ ¼ 2:31, p ¼ :025) and (b) the exercise simple slope was significant only on days 12,13, and 14 of data collection. Therefore, our findings indicate that exercise was associated withincreased positive affect only on the final 3 days of data collection, (days in which a majority ofparticipants reported examinations as their most stressful academic event of the day).ARTICLE IN PRESSTable 2Within subjects associations between exercise, cognitive appraisals, and positive affectVariable Coefficient Standard error t R2 DR2 w2Positive affectDay 0.25 0.07 3.32** .08 .05 29.03Threat 0.07 0.14 0.47 — — 26.41Challenge 0.77 0.18 4.18*** .11 .03 27.00Exercise 0.02 0.03 0.89 — — 36.70Daythreat 0.04 0.04 0.88 — — 36.28Daychallenge 0.07 0.03 2.10* .04 .003 20.16Dayexercise 0.01 0.00 2.82** .06 .001 34.08Challengeexercise 0.02 0.02 1.07 — — 30.34Threatexercise 0.03 0.02 1.69 — — 36.26Negative affectDay 0.08 0.08 0.95 — — 46.65Threat 0.77 0.14 5.42*** .22 .02 32.42Challenge 0.08 0.12 0.66 — — 35.71Exercise 0.03 0.03 0.89 — — 29.59Daythreat 0.03 0.03 0.74 — — 34.74Daychallenge 0.01 0.03 0.46 — — 39.30Dayexercise 0.00 0.00 1.46 — — 27.80Challengeexercise 0.01 0.00 1.01 — — 27.99Threatexercise 0.03 0.01 2.94** .07 .01 35.99*po.05; **po.01; ***po.001.P.R. Giacobbi Jr. et al. / Psychology of Sport and Exercise 8 (2007) 261–274 269Also reported in Table 2 are the effect size estimates, or R-squared values, and the DR2. Thesecalculations reveal the size of the association between challenge and positive affect as well as dayand positive affect were generally small (Cohen, 1988; Raudenbush & Xiao-Feng, 2001). Finally,the results of chi-square tests to determine whether the strength of the within-subjects associationsvaried across participants proved non-significant in all cases with positive affect as the dependentvariable.The results of the model with negative affect as the dependent variable revealed that threatappraisals were significantly related with negative affect while day and exercise were not.Interestingly, the interaction of exercise and threat revealed a significant and positive association
with negative affect while all other interaction terms were not significant suggesting that the
exercise/negative affect relationship was moderated by threat appraisal. The simple slope and
region of significance were calculated with 1.90, 4.46, and 7.02 (M71 SD) representing
meaningful conditional values for low, average, and high threat. This analysis revealed that
exercise was significantly associated with decreased negative affect when threat appraisal was low
(o ¼ 2:06, tð54Þ ¼ 25:26, po:001), while marginally associated with increased negative affect
when threat appraisal was high (o ¼ :12, tð54Þ ¼ 1:97, p ¼ :054). Furthermore, the exercise simple
slope was significantly negative when threat appraisal was between 0 and 2.69, while significantly
positive when threat appraisal was between 7.15 and 9.00. Taken together, our results indicate
that exercise was associated with reductions in negative affect when academic stressors were
mildly threatening, while associated with increases in negative affect when stressors were highly
threatening. The effect size estimates or R-squared values were .22 for the threat/negative affect
relationship and .07 for the exercise/threat interaction.
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