Prokopy, MP, Ingersoll, CD, Nordenschild, E, Katch, FI, Gaesser GA, Weltman A.
Closed-kinetic chain upper-body training improves throwing performance of NCAA Division I Softball players.
Journal of Strength and conditioning 22(6): 1790-1798, 2008

Studie
12 softballspillere ble delt i to grupper der den ene gruppen trente øvelser for overkropp med frivekter og manualer (åpen kinetisk kjede/ ikke kroppsvektbærende) og en gruppe trente med Redcord (lukket kinetisk kjede / kroppsvektbærende). Begge grupper trente 3 ganger per uke over 12 uker. Treningsvolum var likt i de to gruppene. Før og etter treningen ble deltagerne testet for : kasthastighet, benkpress (1RM), dynamisk balanse og isometrisk styrke for skulder fleksjon, ekstensjon, utadrotasjon og innadrotasjon. Gruppen som trente i lukket kinetisk kjede fikk en signifikant økning (3,4%) i kasthastigheten sammenliknet med gruppen som trente i åpen kinetisk kjede (økning 0,5%). Flere av styrketestene tenderte også mot forbedringer i gruppen som trente i lukket kinetisk kjede men pga lavt antall deltagere ble ikke signifikante forkjeller påvist. Forfatterne konkluderer at nevrale adaptasjoner kan være en årsak til den oppserverte forbedringen i gruppen som trente i lukket kinetisk kjede.

Abstract:
Closed–kinetic chain resistance training (CKCRT) of the lower body is superior to open–kinetic chain resistance training (OKCRT) to improve performance parameters (e.g., vertical jump), but the effects of upper-body CKCRT on throwing performance remain unknown.

This study compared shoulder strength, power, and throwing velocity changes in athletes training the upper body exclusively with either CKCRT (using a system of ropes and slings) or OKCRT. Fourteen female National Collegiate Athletic Association Division I softball player volunteers were blocked and randomly placed into two groups: CKCRT and OKCRT. Blocking ensured the same number of veteran players and rookies in each training group. Training occurred three times weekly for 12 weeks during the team’s supervised off-season program. Olympic, lower-body, core training, and upper-body intensity and volume in OKCRT and CKCRT were equalized between groups. Criterion variables pre- and posttraining included throwing velocity, bench press one-repetition maximum (1RM), dynamic single-leg balance, and isokinetic peak torque and power (PWR) (at 180!!s21) for shoulder flexion, extension, internal rotation, and external rotation (ER).

The CKCRT group significantly improved throwing velocity by 2.0 mph (3.4%, p , 0.05), and the OKCRT group improved 0.3 mph (0.5%, NS). A significant interaction was observed (p , 0.05). The CKCRT group improved its 1RM bench press to the same degree (1.9 kg) as the OKCRT group (p , 0.05 within each group). The CKCRT group improved all measures of shoulder strength and power, whereas OKCRT conferred little change in shoulder torque and power scores.

Although throwing is an open-chain movement, adaptations from CKCRT may confer benefits to subsequent performance. Strength coaches can incorporate upper-body CKCRT without sacrificing gains in maximal strength or performance criteria associated with an athletic open-chain movement such as throwing.