Citation:Low, C and Emmonds, S and Helme, M (2019) Unilateral leg strength: Relevent to Rugby LeagueSpeed? In: United Kingdom Strength and Conditioning Association National Conference, 15 June2019 - 16 June 2019, Stadium MK, Milton Keynes. (Unpublished)

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@markhelme1

Unilateral leg strength: relevant to Rugby League speed?

Mark Helme, BSc, PGCE, PGD, ASCC PhD Candidate Leeds Beckett University- Doctoral research.

Rugby League: Speed

@markhelme1

Total number of high intensity accelerations 79.5±8, Gabbett (2013)

Mean maximum velocity9.0±1.03m/s for backs and 8.47±0.7m/s, McLellan and Lovell (2013)

Gabbett (2012) total sprints per game as, 36.5±9.3

67.5% Sprints are between 6m and 20m Gabbett (2012)

Rugby League: Strength

@markhelme1

Higher in elite RL players compared to sub-elite, (Baker and Newton, 2008)

Related to tackle success and tackle success under fatigue, (Gabbett, 2008), Speranza et al. (2015)

Strength and Linear Speed

@markhelme1

Strength gains correlated with sprint performance (r = 0.6 – 0.78), Styles et al. (2016).

Strong correlations between 1RM BS and 10m (r = -0.94) , Wisløff et al. (2004).

Significant increases were observed in changes in absolute and relative strength (p<0.001), Comfort et al. (2012), Keiner et al. (2014) .

Strength and Change of direction speed

@markhelme1

Leg Strength COD Time

(1RM BS (Bourgeois Ii et al., 2014), 3RM BS (McCormick et al., 2014), IMTP (Spiteri et al., 2014, Thomas et al., 2018),

@markhelme1@markhelme1

Stronger Players Better players

Tackle Change direction

Sprint

Unilateral leg strength: relevant to Rugby League speed?

• It was hypothesized that unilateral leg strength would correlate with performance in sprint and CODS measures.

@markhelme1@markhelme1

Experimental approach

• Unilateral Leg strength (asymmetry)• Rear foot elevated split squat (RFESS) five repetition maximum (5RM)

• Validated by McCurdy et al (Strength) and Helme et al (asymmetry) (Under review)

• Linear Speed• Standing 20m sprint (0-10m, 10m-20m Splits)

• Time, mean velocity, momentum

• Change of direction speed• Modified 5-0-5 test

• Time, change of direction deficit

@markhelme1

Participants

• With institutional ethical approval, 78 subjects were recruited from three RL teams. When exclusion criteria were applied (free from injury for six weeks prior to testing and available to attend both test dates) 28 were removed and 50 subjects were retained for testing. • Post-hoc power analysis (G*power) found a 68% probability for an effect size

of 0.5 and alpha level of error of 0.05, for this sample size.

@markhelme1

Elite academy

(n=32)

Semi-professional

(n=18)

Whole Group

(n=50)

Age (years) 17.3 ± 1 25.3 ± 5.3 20.71 ± 5.1

Mass (kg) 85.6 ±11.5 92.7 ±9.6 88.2 ±11.2

Height (m) 1.81 ± 0.1 1.83 ± 0.1 1.82 ± 0.1

Rear Foot Elevated Split Squat 5RM

• Review of the validity and reliability of the RFESS 5RM as a measure of leg strength symmetry• Paper currently under review (JSCR)

• Bar loads between test and re-test conditions a most likely very large positive correlation (r =0.93, CL 0.88-0.96) and an excellent level of reliability was found (ICC = 0.93 CL 0.88-0.96).

@markhelme1

@markhelme1

No correlation p >0.05

@markhelme1

Modified 5-0-5 time, let side (s)

Modified 5-0-5 time, right side (s)

Mean modified 5-0-5 time, (s)

Change of direction deficit, left side (s)

Change of direction deficit, right side (s)

Mean change of direction deficit (s)

Likely Small Negative Correlation.

Likely Small Negative Correlation.

Likely Small Negative Correlation.

Likely Small Negative Correlation.

Likely Small Negative Correlation.

Likely Moderate Negative Correlation.

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

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Effect Size (95% CI)

Comparison of the effect sizes for correlation between 5RM RFESS using the mean of both legs and change of direction speed performance

No correlation p >0.05

@markhelme1

@markhelme1

Modified 5-0-5 mean (s)

Modified 5-0-5 right (s)

Modified 5-0-5 left (s)

Change of direction deficit right (s)

Change of direction deficit mean (s)

Change of direction deficit left (s)

Almost Certainly Moderate Negative Correlation**

Almost Certainly Moderate Negative Correlation**

Almost Certainly Moderate Negative Correlation **

Almost Certainly Moderate Negative Correlation**

Most Likely Moderate Negative Correlation**

Most Likely Moderate Negative Correlation*

-1.5 -1.3 -1.1 -0.9 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5

Mag

nit

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ase

d in

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Effect size (95% CI)

Comparison of the effect sizes for correlation between 5RM RFESS, relative to body mass, using the mean of both legs and change of direction speed performance

@markhelme1

Momentum 0-10m (m/s/s)

Momentum 10-20m (m/s/s)

20m (s)

10m (s)

Mean velocity 0-10m (m/s)

Mean velocity 10-20m (m/s)

Almost Certainly Large Negative Correlation**

Almost Certainly Moderate Negative Correlation **

Likely Small Negative Correlation **

Unclear Association.

Unclear Association.

Likely Moderate Positive Correlation. **

-1.5 -1.3 -1.1 -0.9 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5

Mag

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e B

ase

d in

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Per

form

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Effect size (95% CI)

Comparison of the effect sizes for correlation between 5RM RFESS, relative to body mass, using the mean of both legs and linear speed performance

@markhelme1

The relationship between body mass and mean unilateral leg strength, relative to body mass.

Almost Certainly Large Negative Correlation, p = >0.01

Mean relative strength 1.01 ±0.17

@markhelme1

Conclusions and applications• Absolute unilateral strength was not found to be associated with either

linear or CODS.

• Relative unilateral leg strength is associated with improved CODS and linear sprint speed.

• Momentum was negatively linked to relative strength• Lighter people were stronger.

• Elite players are heavier than sub-elite and academy players.

• Heavier players (forwards) need to increase relative strength, to that of or greater than lighter (backs) players• Reduce fat mass• Increase lean tissue• Increase absolute strength.

@markhelme1

Future directions and research

@markhelme1

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@markhelme1

Contact details

• Email:• Mark.helme@leedsbeckett.ac.uk

• Twitter • @markhelme1

• LinkedIn• Mark Helme

• ResearchGate• Mark Helme

@markhelme1

References• Baker DG and Newton RU. Comparison of lower body strength, power, acceleration, speed, agility, and sprint momentum to describe and compare

playing rank among professional rugby league players. The Journal of Strength & Conditioning Research 22: 153-158, 2008.

• Bourgeois Ii FA, McGuigan MR, Winchester JB, Brem RW, and Wyatt FB. THE RELATIONSHIP BETWEEN STRENGTH AND CHANGE OF DIRECTION PERFORMANCE IN COLLEGE FOOTBALL PLAYERS. Journal of Australian Strength & Conditioning 22: 132-134, 2014.

• Comfort P, Haigh A, and Matthews MJ. Are Changes in Maximal Squat Strength during Preseason Training Reflected in Changes in Sprint Performance in Rugby League Players? The Journal of Strength & Conditioning Research 26: 772-776, 2012.

• Gabbett TJ. Sprinting Patterns of National Rugby League Competition. The Journal of Strength & Conditioning Research 26: 121-130, 2012.

• Gabbett TJ. Influence of the Opposing Team on the Physical Demands of Elite Rugby League Match Play. The Journal of Strength & Conditioning Research 27: 1629-1635, 2013.

• Gabbett TJ, Jenkins DG, and Abernethy B. Correlates of Tackling Ability in High-Performance Rugby League Players. The Journal of Strength & Conditioning Research 25: 72-79, 2011

• Gabbett TJ, Jenkins DG, and Abernethy B. Relative importance of physiological, anthropometric, and skill qualities to team selection in professional rugby league. J Sport Sci 29: 1453-1461, 2011.

• Gabbett TJ, Kelly JN, and Sheppard JM. Speed, Change of Direction Speed, and Reactive Agility of Rugby League Players. The Journal of Strength & Conditioning Research 22: 174-181, 2008.

• Hammami M, Negra Y, Billaut F, Hermassi S, Shephard RJ, and Chelly MS. Effects of Lower-Limb Strength Training on Agility, Repeated Sprinting With Changes of Direction, Leg Peak Power, and Neuromuscular Adaptations of Soccer Players. The Journal of Strength & Conditioning Research 32: 37-47, 2018.

• Hausler J, Halaki M, and Orr R. Player Activity Profiles in the Australian Second-Tier Rugby League Competitions. International Journal of Sports Physiology & Performance 11: 816-823, 2016.

@markhelme1

References• McBride JM, Blow D, Kirby TJ, Haines TL, Dayne AM, and Triplett NT. Relationship Between Maximal Squat Strength and Five, Ten,

and Forty Yard Sprint Times. The Journal of Strength & Conditioning Research 23: 1633-1636, 2009.

• McLellan CP and Lovell DI. Performance Analysis of Professional, Semiprofessional, and Junior Elite Rugby League Match-Play Using Global Positioning Systems. The Journal of Strength & Conditioning Research 27: 3266-3274, 2013.

• McCurdy K. Technique, Variation, and Progression of the Rear-Foot-Elevated Split Squat. Strength Cond J 39: 93-97, 2017.

• McCurdy K and Conner C. Unilateral support resistance training incorporating the hip and knee. Strength Cond J 25: 45-51, 2003.

• McCurdy K, Langford GA, Cline AL, Doscher M, and Hoff R. The reliability of 1- and 3rm tests of unilateral strength in trained and untrained men and women. Journal of Sports Science & Medicine 3: 190-196, 2004.

• Sheppard J and Young W. Agility literature review: Classifications, training and testing. J Sport Sci 24: 919-932, 2006.

• Speirs DE, Bennett MA, Finn CV, and Turner AP. Unilateral vs. Bilateral squat training for strength, sprints, and agility in academy rugby players. The Journal of Strength & Conditioning Research 30: 386-392, 2016.

• Styles WJ, Matthews MJ, and Comfort P. Effects of Strength Training on Squat and Sprint Performance in Soccer Players. The Journal of Strength & Conditioning Research 30: 1534-1539, 2016.

• Wisløff U, Castagna C, Helgerud J, Jones R, and Hoff J. Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players. Brit J Sport Med 38: 285-288, 2004.

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