II. Song dien nhanh va ngan noi len tinh hinh nao khi hoat dong X Noi len lao dong tri oc bat dau.
O phan tren da noi ve nguyen ly hoa hoc sinh vat ciia sir bien hoa phat sinh trong co the v an d on g kh
van dong. De mo ta mot cach de dang nh iing p han kho hieu, d day mdi thu gon trong pham vi phan ticl- nhiing bien hoa ciia m ot bo phan nao cu a he thong va khi quan.
Chung ta co the giai thich khi van dong trong co the phat sinh nhiing bien hoa gi, giai thich he thong trung uong than kinh va hoat dong cua he than kinh cao cap ciia no da thuc hien thong nhat nhvr the nao ma phat sinh tac dung chi phoi moi qua trinh sinh ly.
Quan he khang khit giiia co nang sinh ly cua co the va hoat dong than kinh cao cap co the nhin th a y trong thuc nghiem ve “hoat dong ciia tri tudng t u o n g ” . V i du tren mot so' cong nhan lao dong tay chan th u a n thuc viec mot nganh nghe nao dp hay m ot van don g vien da tting dat nhieu lan huy chuong thay : tri tudng tu o n g trong giay phut cua cac dong tac va v an dong nay tim dap nhanh len. Hay nguoi nhay mot do cao mdi, thuon g thuong ngoi xuo'ng n h im m i t lai, thu m inh co g i n g
tudng tuong nhting chi tiet khi nhay qua do cao mdi . Trong khi tuong tuong nen nhay nhu the nao m oi nhay vuot qua tam cao ciia sao duoc, mo hoi toat ra tren da trudc do.
Hoat dong than kinh cao cap duong nhien la co a nh hudng den co nang ciia khi quan trong noi tang khi tri tudng tu on g hoat dong; nhung thuOng thuOng co mot dieu kien : su hoat dong do phai la hoat dong ma nguOi duoc thuc nghiem da thanh thoi quen roi, va da thanh dieu kien phan xa doi vdi hoat dong ciia khi quan noi tang; bdi vi hoat dong do da co y thufc thuc tien di di lai lai tuong doi nhieu lan. H oat don g ciia tri tudng tuong se de gay ra hien tu on g tim dap nhanh len va nhUng bien hoa trong cac co nang cu ng k h ac thudng, la vi luc thuc te tien hanh van dong cu n g la luc bien hoa hoa hoc phat sinh ra. Hon ntia ngudi v an dong ciing da tting nhieu lan trai qua bien hoa do lap di lap lai truOc do.
Bien hoa cua ho hap va m ach m au trong khi oc tucrng tu o n g van dong : van dong vien d u o c cai djnh khi th u c nghiem tro ng buong rieng, ngucri huan luyen vien de nghi vo i van dong vien tu o n g tu o n g chuan bj chay 100 th u o c tren san van dong hay trong p h o n g ta p tieu chuan co dinh.
D iin bien cua thd
Mot vi du khac, noi ro hoat dong cua he thong than kinh cao cap co anh hudng den cac khi quan va he thong khac con co “trang thai khdi thi” (1) (nhieu kieu thi : thi len ldp, thi kiem tra ky thuat, thi tot nghiep hoac chuan bi lam m ot viec gi do co tinh chat kiem tra nang luc, sue khoe, benh tat...). Trang thai khdi thi la trang thai khdi dau su bien hoa cua m ot qua trinh sinh ly phat sinh trong co the trudc khi bat dau cuoc dua, tham chi ca den trudc gid huan luyen b i t dau. “T ra n g thai khdi thi” chia lam hai loai : m ot loai phat sinh nhieu
(1) Trang thai truoc gicr thi b it dau chuan bi goi chung la trang thai khoi thi
gid, tham chi nhieu ngay truOc khi cuoc dua bat dau; mot loai phat sinh ngay vai phut, vai gicr khi cuoc dua bat dau.
Bien hoa cua nhiing qua trinh sinh ly do phat sinh trudc cuoc dua hay khi cuoc dua bat dau la ket qua su hinh thanh phan xa co dieu kien doi vdi hoan canh va thdi gian s i p tien hanh cuoc dua. Dong thdi nhiing bien hoa do dua tren cor sd nhUng bien hoa tinh vi va nghiem tuc cua tra n g thai ccr n&ng trong he th o n g than kinh trung ucmg ciia van dong vien.
Trong khi phat sinh ra “trang thai khdi th i” thudng thudng hung phan ciia than kinh trung uomg len cao; dieu do chung minh la ngudi van dong do da chuan bi tot cho co the khi tien hanh van dong.
Trudc gid thi ky trudc gid kiem tra tim th u on g thuOng dap co phan nhanh, ho hap sau hon, lam cho bo may ho hap va tuan hoan cang nhanh chong phat huy nang luc hoat dong ciia no khi van dong. Nhu truOc gid thi dau, chat dudng trong mau tang len va chat duong de cho bap thit can phai tieu hao cang nhieu hon.
Co the co truon g hop rat it nao do, hung phan than kinh trung uong len cao qua m uc thich d ang va cu ng co nhung cuoc van don g phan khdi den noi nhin khong tudng tuong het tinh hinh xung quanh, khong kim ham noi nhung dien bien xuc cam ve nh un g d on g tac ciia m inh, ngudi nong, ngudi bang kh uan g, b o n c h o n , co
luc thoang nhu mat cam giac, v.v... T ra n g thai hung phan qua m uc do thudng goi chung la “ben h nong ngudi” , benh nay neu la van dong vien the thao co the lam giam siit nang luc van don g ciia v an don g vien khi thi dau, anh hudng khong tot den thanh tich van dong. 66 105 10% mach nhay 114 125 148% 18%
huyet ap cao nhat
glycogen acid lactic
Hinh ben trai: Hang ngay trade khi tap luyen Hinh ben ph a i: Trade khi di thi dau
Thu tu theo cac cot tu trai sang phai cua moi hinh : Tan so mach nhay - so huyet ap cao - so luong duong - acid lactic trong mau - so sanh 2 sa do thuc nghiem. Chung ta thay tinh hinh xay ra bien hoa trurirc khi thi dau, chi tieu nang cao len ro ret (hinh ben phai). Do la mot thi du da tac dong kich thich anh hudrng ciia vo nao ddi vdi hoat dong ciia tim va qua trinh thay cu ddi mdi.
N goai hien tuqrng hung phan tang len, co n th a y co dien bien hung phan he th o n g than kinh trun g uong giam siit di; su giam sut do lam cho qua trinh uc che ph at trien la nhip cau khong tot tao ch o v an don g vien thieu q u yet tam doi vdi cu o c dua s i p b i t dau, do do lam ha thap thanh tich khong lu o n g cua su van dong xuong.
Muon khac phuc “trang thai khdi th i” binh thudng do, tuc la hien tuong hung phan phai dien bien theo nhip do sinh ly co nang khong qua thap hoac qua cao. Neu qua thap, qua cao se anh hudng khong co loi den thanh tich van dong, neu gap truOng hop tren chung ta dong vien y chi tu tin k h i n g djnh du oc minh tat thang va lam duoc.
C o nang sinh ly thong thuOng cua vo nao da noi tdi trong nh ung thi du tren ve hoat don g ciia tri tudng tu on g hay “trang thai khdi th i” luon luon deu co mot tac dung ve m at nay.
Lien he gitia phan xa co dieu kien vo 1 nhiing bien doi sinh ly, phat sinh ra tinh chat va cuong do ciia van dong. Tap quan trong qua trinh thuc te van dong ciia van dong co the dan den mot tinh hinh nhu sau : Chung ta bao cho mot nguoi lao dong vac 100 kg di 50m nhung thuc te chi vac co 50kg va di co 25m hoac mot van dong vien biet trudc la phai chuan bi chay 100 thuoc nhung den khi chay duoc nua dudng (50 thudc) chung ta bao van dong vien diing lai kiem tra thi chung ta thay khoi lugng oxy da tieu hao nhieu hon khoi lugng oxy thuc te can thiet. Khi chung ta bao cho van dong vien chay 50 thudc hoac m ot ngudi lao dong vac 50kg khoi lugng oxy can thiet giam di rat nhieu so vdi khoi lugng oxy tieu hao khi chung ta bao chay 100 thudc hoac vac
100 kg van dong.
Cho nen thay rang khong nhting ban than ciia van dong ma con ca hoat dong than kinh cao cap ciia van dong (sue tudng tugng ve van dong sap bat dau va chuan bi tinh than de hoan thanh van dong do) cung co the dien bien cudng do ciia bien doi sinh ly, vi the no cung da tu phat sinh nang lugng can thiet de hoan thanh van dong.
Trong cac vi du trinh bay tren, chung ta thay rang neu cudng do van dong du dinh trudc ldn hon cudng do van dong thuc te thi su chuan bi tinh than lam cho khdi lugng oxy tang len nhieu hon va khdi lugng . tieu hao cung tang len.
Neu cudng do van dong dvr dinh trudc be hon cudng do van dong thuc te, thi dien bien chuan bi tinh than ve mat sinh ly khong thich hop, vi r i n g nang luc hoat dong cac khi quan va cac he (tuan hoan, ho hap,...) se tien trien cham hon, do do viec thuc hien van dong cung tien hanh cham theo.
Vi the nen m6i ngudri thay hay m oi ngudi quan ly va huan luyen deu co nhiem vu lam cho nguori van dong co su chuan bi tinh than dung d i n ve cu dng do cua sue s i p van dong tien hanh. Co nhu the mriri co the lam cho ngixdi van dong ciia minh n i m duorc khdi luong, muc do phat trien tieu chuan de danh gia trinh do van donr: ciia minh, co the udc luong duoc mot cach ro rang ve cudng do va sue can thiet de tien hanh mon van dong nay hay mon van dong kia sap tdi (thi du : sue bat, sue dap chan, sue chiu dung, sue vac, hay toe do chay,...).
Chung ta da thay viec trinh bay mot cach kha tudng tan ve nguyen t i c khach quan tu giac trong qua trinh dieu khien giang day va huan luyen. Co n h u n g thi du ke tren, chiing ta da thay m uon cho ngudi v an dong nam duoc tieu chuan de tu danh gia sue v an d o n g ciia minh la m ot trong nhUng nhiem vu trudc h et la ciia ngudi thay giao, ngudi dieu khien, cap chuyen gia hoSc huan luyen vien.
Tom lai truac khi b i t dau van dong cof the co the phat sinh ra rat nhieu bien hoa sinh ly. N hung bien hoa sinh ly do gay ra la bai su hoat dong ciia ban than no va vai muc do nao do la do anh huang ciia vo nao truac khi van dong quyet dinh.
Nhiing bien hoa sinh ly do, nhu da neu a tren, la ket qua cua su lien he phan xa dong bo co dieu kien dat giiia vo nao vai trung khu dai nao, dieu tiet hoat dong ciia cac khi quan va qua trinh thay cu doi mai trung uang than kinh dai nao gom nhieu trung khu (goi t i t la vung) nhu trung khu ho hap, trung khu huyet quan, v.v.. cac trung khu nay phat sinh hung phan den muc co luc co the gay ra huyet ap cao.
Nhung khi ren luyen van dong thuc su thi tinh hinh thuang dien bien phuc tap, hung phan a he thong trung uang than kinh tang len. Dai nao dua tin hieu van dong den bap thit bang tuy song, re than kinh truac ciia tuy song va bang nhiing than kinh co lien quan khac. Trong bap thit nha co dau than kinh ciia than kinh bap thit, hung phan co the truyen tu than kinh den bap thit. Qua trinh nay vo cung phuc tap, no dua vao su lien quan giiia qua trinh hoa hoc va hien tugng dien ca the.
Qua trinh hung phan chuyen tii than kinh vao b i p thit gay ra m ot loat phan ung hoa hoc phuc tap. B i t dau la albumin b i p thit co lai va phan giai A.T. P.
Dong thai phan ung thieu oxy va phan ling oxy hoa cung bat dau hoat dong.
Can nha rang : kich thich than kinh van dong noi chung chi truyen tai de bap thit co ca hoi tham gia van dong dung luc.
Do la nha co su bien doi van dong vo cu n g tinh vi, chinh xac va phuc tap cua vo nao, tuc la nha co bien dong ma Paplop goi la cong tac cua “ vo n a o ” .
Ty le hai qua trinh hung phan va uc che cua vo nao la hai qua trinh bien doi khong n gu ng de bao dam su hai hoa luan luu nhanh chong va chinh xac, nghia la m ot bo phan b i p thit nay tham gia v an d on g thi m ot bo phan b i p thit khac dugc “giai trii v an d o n g ” .
Nhung khong phai nhung kich thich nao cu n g lam cho than kinh van dong deu co the truyen vao bap thit de tham gia van dong dung luc va chinh xac, nh at la doi vgi nguai mai tham gia van dong. Bai vi ho chua nam dugc day du ky thuat, thoi quen van d on g nen thuang thu hut bat ca nhung bo ca b i p thit ma luc bay gia khong can den van don g ciing phai Liieo da tham gia van dong, cho nen co liic lam can tra van dong khong tien hanh binh thuang, vuan ngtrang, giam thap thanh tich van dong.
Van de neu tren chung ta quan sat thu tii m ot nguori lao dong nang hoac mai tap chay “doc toan sure chay 100 m et hay m ot vai doan nao trong q u a n g 100 m e t ” .
Theo le thuang thanh tich cua ho thap hon may phan muoi giay so vdi thanh tich chay khong bao trudc hoac lao dong khong bao trudc.
Sd di nhu the la vi ngudi van dong chua nam duoc hoan toan cam giac bap thit ciia minh. Muon hoat dong het sure, nhung thuc te la da lam cho nhung b i p thit chua can van dong den cung cang thang. Do do cac thiic nghiem cho thay chay “mot cach ap d a t” mot la de bi uc che kho khan, hai la khong tiet kiem duoc nang luong tieu hao khi van dong. Nhung sau do lai de cho ngudi van dong hoat dong cham di doi chut thi ho khong thay cang t h i n g ntia.
To'c do cham va stic bat van nhu lan trudc khong thay doi, nhung thanh tich lan nay so vdi lan trudc co the thudng cao hon tti 0,2 den 0,3 giay.
Cac nha khoa hoc d Vien khoa hoc nghien cuu sinh ly Leningrat va cac vien ciia cac nude da tien hanh quan sat nhieu lan va da chting minh rang : biet phan phoi mot cach chinh xac do cang t h i n g cho bap thit va biet dua nhting bo soi b i p thit can thiet vao tham gia van dong, no gop phan co mot y nghia rat to ldn. No lam cho bap thit thoai mai, phan ting tham gia van dong dung liic, la m ot trach nhiem cue ky quan trong. Nang luc van dong do ngudi chuyen gia hoac ngudi dieu khien su van dong phai luon duoc ciing co' trong qua trinh n i m ky thuat van dong va trong qua trinh ren
l u y e n . Ca sd nam dugc nang luc do co tac dung phan tich dugc dien bien va chinh xac ciia qua trinh hung phan vo nao. (Tac dung phan tich d day la su giam sat va phan biet thdi cor de dua bap thit co lien quan den van dong vao tham gia van dong). Nam duac cac phan tich tren doi hoi qua trinh lam viec nghien ctiu phai co giao trinh, hoac quang ba bai ban mdi nam bat duac.
Nhiing cam giac b i p thit gay ra bdi m ot bo phan b i p thit nao d tren m at co lai, ma thud ng xay ra khi chung ta mim cudi hay chung ta nhan mat, nhd su giiip dd ciia vo nao ma cam giac do deu anh hudng den tinh hinh toan bo ca nang khi quan b i p thit.