title: Neuromuscular differences between prepubescents boys and adult men during drop jump.
abstract: The purpose of the present study was to determine the lower extremities biomechanical differences between prepubescent and adult males during drop jumps (DJs). Twenty-four untrained males (12 prepubescents, 12 adults) performed DJs from 20 cm height. Kinematics of the lower extremities were captured, in addition with vertical ground reaction forces (vGRFs) and EMG activity of the gastrocnemius medialis (GM), soleus (SOL) and tibialis anterior (TA) muscles. The results showed that men jumped higher, as expected, but their knees were more flexed prior to landing, and their preactivation level was higher and longer in duration compared to prepubescent boys. During landing, men had shorter contact times, lower vGRF normalized to body mass, and less maximal knee joint flexion. Regarding EMG activity men presented higher stretch reflex and higher EMG activity during the braking phase but the level of coactivation (TA to GM + SOL ratio) was lower. It is seems that pre-landing and landing patterns during a complex task such as DJ are affected by physical development. There are indications that men had higher performance in a DJ than prepubescent boys because they activated more effectively their muscles during the preactivation and braking phase. The above-mentioned data support the hypothesis that prepubescent boys might be inferior in optimal regulation of their muscle-tendon unit stiffness.
authors.affiliation: Laboratory of Coaching and Sport Performance, Department of Physical Education and Sport Sciences, Aristotle University of Thessaloniki, 54006 Thessaloníki, Greece.
authors.forename: Savvas
authors.initials: S
authors.lastname: Lazaridis
authors.forename: Eleni
authors.initials: E
authors.lastname: Bassa
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Patikas
authors.forename: Giannis
authors.initials: G
authors.lastname: Giakas
authors.forename: Albert
authors.initials: A
authors.lastname: Gollhofer
authors.forename: Christos
authors.initials: C
authors.lastname: Kotzamanidis
mesh_terms: D000328:Adult; D000367:Age Factors; D001696:Biomechanical Phenomena; D002648:Child; D004576:Electromyography; D015444:Exercise; D006801:Humans; D007719:Knee Joint / Q000294:innervation; D035002:Lower Extremity; D008297:Male; D018482:Muscle, Skeletal / Q000254:growth & development / Q000294:innervation*; D009469:Neuromuscular Junction / Q000254:growth & development / Q000502:physiology*; D011627:Puberty; D012026:Reflex, Stretch; D013997:Time Factors; D014741:Video Recording; D055815:Young Adult
references.citation: J Strength Cond Res. 2006 May;20(2):441-5
references.pmid: 16686577
references.citation: Arch Phys Med Rehabil. 1984 Sep;65(9):517-21
references.pmid: 6477083
references.citation: J Appl Physiol (1985). 1999 Dec;87(6):2090-6
references.pmid: 10601154
references.citation: Int J Sports Med. 1984 Feb;5(1):19-22
references.pmid: 6698678
references.citation: Int J Sports Med. 2001 Feb;22(2):138-43
references.pmid: 11281617
references.citation: Electromyogr Clin Neurophysiol. 2004 Sep;44(6):339-48
references.pmid: 15473345
references.citation: J Sports Med Phys Fitness. 2009 Mar;49(1):35-43
references.pmid: 19188894
references.citation: Sports Med. 1998 Jan;25(1):37-62
references.pmid: 9458526
references.citation: Clin J Sport Med. 2006 Jan;16(1):56-62
references.pmid: 16377977
references.citation: J Physiol. 2003 Aug 1;550(Pt 3):985-93
references.pmid: 12813158
references.citation: J Appl Physiol (1985). 2007 Jun;102(6):2352-60
references.pmid: 17347384
references.citation: Br J Sports Med. 2000 Aug;34(4):293-6
references.pmid: 10953904
references.citation: Exp Brain Res. 2008 Sep;190(1):71-9
references.pmid: 18553072
references.citation: Am J Sports Med. 2005 Jun;33(6):831-42
references.pmid: 15827359
references.citation: BMC Musculoskelet Disord. 2006 Mar 07;7:22
references.pmid: 16522210
references.citation: Eur J Appl Physiol Occup Physiol. 1993;67(6):549-53
references.pmid: 8149936
references.citation: Eur J Appl Physiol Occup Physiol. 1998 Oct;78(5):432-40
references.pmid: 9809844
references.citation: J Appl Physiol (1985). 2003 Jul;95(1):64-72
references.pmid: 12626487
references.citation: J Appl Physiol (1985). 2007 Oct;103(4):1276-83
references.pmid: 17690197
references.citation: Am J Sports Med. 2006 Mar;34(3):375-84
references.pmid: 16282578
references.citation: Med Sci Sports Exerc. 2007 Jan;39(1):159-70
references.pmid: 17218898
references.citation: J Electromyogr Kinesiol. 2000 Oct;10(5):361-74
references.pmid: 11018445
references.citation: J Electromyogr Kinesiol. 2006 Aug;16(4):342-51
references.pmid: 16406603
references.citation: Br J Sports Med. 2005 Jan;39(1):10-4
references.pmid: 15618332
references.citation: Am J Sports Med. 2005 Feb;33(2):197-207
references.pmid: 15701605
references.citation: Can J Appl Physiol. 1997 Apr;22(2):117-32
references.pmid: 9140666
references.citation: Int J Sports Med. 2007 Jan;28(1):66-71
references.pmid: 17024641
references.citation: Eur J Appl Physiol. 2002 Nov;88(1-2):76-84
references.pmid: 12436273
references.citation: J Electromyogr Kinesiol. 1997 Sep;7(3):179-86
references.pmid: 20719703
references.citation: J Appl Physiol (1985). 2005 Jul;99(1):217-23
references.pmid: 15705735
references.citation: Muscle Nerve. 2007 Sep;36(3):357-63
references.pmid: 17487867
references.citation: Clin J Sport Med. 2006 Jul;16(4):311-5
references.pmid: 16858214
references.citation: J Appl Physiol. 1968 Jan;24(1):21-32
references.pmid: 5635766
references.citation: Med Sci Sports Exerc. 1999 May;31(5):708-16
references.pmid: 10331892
references.citation: Br J Sports Med. 2008 Jul;42(7):561-6
references.pmid: 18308891
references.citation: J Electromyogr Kinesiol. 2008 Jun;18(3):455-65
references.pmid: 17196828
references.citation: J Biomech. 2000 Oct;33(10):1197-206
references.pmid: 10899328
references.citation: J Neurophysiol. 1988 Sep;60(3):1110-21
references.pmid: 3171659
references.citation: Clin J Sport Med. 2006 Jul;16(4):298-304
references.pmid: 16858212
references.citation: Exp Brain Res. 2002 Feb;142(3):354-64
references.pmid: 11819044
references.citation: J Electromyogr Kinesiol. 2001 Oct;11(5):355-64
references.pmid: 11595555
references.citation: Percept Mot Skills. 1996 Dec;83(3 Pt 1):1019-41
references.pmid: 8961340
references.citation: Am J Sports Med. 2005 Dec;33(12):1853-60
references.pmid: 16157852