Reliability and Usefulness of the 30-15 Intermittent Fitness Test in Rugby League

Abstract

This study examined the reliability and usefulness of the 30-15 Intermittent Fitness Test (30-15(IFT)) within rugby league. Fifty-five young rugby league players participated in the study. These included representative players from Under 16s (n = 19; 15.6 ± 0.3 years; 78.1 ± 10.9 kg), Under 18s (n = 21; 17.4 ± 0.5 years; 86.9 ± 11.2 kg), and Under 20s (n = 15; 19.4 ± 0.5 years; 95.9 ± 8.7 kg) squads within a professional rugby league club. Players performed the 30-15(IFT) twice within 9 days of each other. Maximal intermittent running velocity (V(IFT)) and heart rate at exhaustion (HR(peak)) were collected for both tests. Intraclass correlation coefficients (ICCs) for the "Combined" and Under 20s were very large (r > 0.7), whereas the ICCs for Under 16s and Under 18s were almost perfect (r > 0.9). Coefficients of variation were 1.9% (95% confidence interval, 1.6-2.4) for the combined test-retest of the 30-15(IFT) and 0.6% (0.5-1.0) for HR(peak). As the typical error of measurement (TE) (0.36 km·h⁻¹) was greater than the smallest worthwhile change (SWC) (0.21 km·h⁻¹) value, the usefulness of the V(IFT) was rated as "marginal." The TE for HR(peak) was similar to the SWC, rating the usefulness of this variable as "OK." Despite the usefulness of the 30-15(IFT) being deemed Marginal, a change as small as 0.5 km·h⁻¹ (1 stage) in V(IFT) could be considered substantial or "real." As a consequence, the 30-15(IFT) presents as both a reliable and useful field test in the assessment of intermittent fitness for rugby league players.

Reliability, Validity and Usefulness of 30–15 Intermittent Fitness Test in Female Soccer Players

“…The V IFT reliability findings herein were (TE = 0.31 km/h, CV = 1.8%; ICC = 0.91) were similar to previous investigations; that observed low typical error (CV = 0.8 to 1.9%) in male and female team sport athletes (e.g., soccer, ice hockey, rugby and handball) (Buchheit, 2005; Buchheit et al, 2011; Scott et al, 2015; Thomas et al, 2015). A small learning effect for the 30–15 IFT was observed, as a “small” non-significant increase in V IFT was observed from the first to the second testing session; this most likely occurred to the group's lack of experience in performing the test.…”

“…In light of the fact that the Yo-Yo IR1 and 30–15 IFT assess different physical capacities, a large correlation ( r = 0.75) was observed between the two intermittent fitness tests with similar levels of sensitivity following an 8 week training intervention in male soccer players (Buchheit and Rabbani, 2014). The high reliability of HRpeak (TE = 2 b.p.m; CV = 1.2%; ICC = 0.94) during the 30–15 IFT in elite female soccer players further supports the outcomes of previous research (Buchheit et al, 2011; Scott et al, 2015). The sample size used herein for 30–15 IFT test–retest reliability ( n = 16) and validation ( n = 13) were characterized as small; however the high reliability outcomes annulled the small sample size (Hopkins et al, 2001).…”

“…Due to relationship between HRpeak and VO 2max in field based tests (Scott et al, 2015) validation of 30–15 IFT in comparison to a CT is justified for cardiorespiratory and cardiovascular performance. Large and very large linear relationships were observed between the 30–15 IFT and CT for VO 2max ( r = 0.67) and HRpeak ( r = 0.77), which supports the validity of the 30–15 IFT for assessing maximal aerobic fitness in female soccer players.…”

“…It has since been validated for elite ice hockey (Buchheit et al, 2011), male rugby (Scott et al, 2015), male semi-professional soccer (Thomas et al, 2015), and basketball (Buchheit, 2008, 2010) players. The reliability and effectiveness of 30–15 IFT to monitor intermittent fitness changes was also demonstrated in the above studies.…”

Physical Profiles of Regional Academy Netball Players

“…Further, significant differences in VIFT were observed between under 15 and under 17 (16.40 ± 0.83 vs. 17.56 ± 1.30; p = 0.014) age categories, in agreement with recent work demonstrating increases in VIFT as small as 0.5 km•hˉ¹ to be considered 'real' and meaningful in male rugby league and female handball players. 41,42 Taken together, these findings suggest improvements in VIFT could be deemed 'real', however further research is needed to support this contention.…”