THE INFLUENCE OF LOW LOAD LUMBAR EXERCISE TRAINING ON THE DEVELOPMENT OF ISOLATED LUMBAR FLEXOR AND EXTENSOR MUSCLE STRENGTH IN SEAFARERS

Abstract

The purpose of this study was to evaluate the low load lumbar flexion and extension exercise training on the development of isolated lumbar extension and flexion strength. Isometric torque of the isolated lumbar extension and flexion muscles was measured at two positions (0° and 30° range of motion) on 54 healthy men before and after 8 weeks of low load lumbar flexion and extension exercise training. Subjects were assigned in two groups, the first (27) trained 3 times/week with low load lumbar flexion and extension exercise and the second (control, 27) did not train. Post training isometric strength values describing isolated lumbar extension and flexion strength improved in greater extent for the low load lumbar flexion and extension exercise group in both angles (p<0.05) relative to controls. These data indicate that low load lumbar strength exercise training is an effective method of improving lumbar extension and flexion muscles strength.

Keywords: seafarers, lumbar, flexion, extension, isometric, low load, exercise

Abstract

The purpose of this study was to evaluate the low load lumbar flexion and extension exercise training on the development of isolated lumbar extension and flexion strength. Isometric torque of the isolated lumbar extension and flexion muscles was measured at two positions (0° and 30° range of motion) on 54 healthy men before and after 8 weeks of low load lumbar flexion and extension exercise training. Subjects were assigned in two groups, the first (27) trained 3 times/week with low load lumbar flexion and extension exercise and the second (control, 27) did not train. Post training isometric strength values describing isolated lumbar extension and flexion strength improved in greater extent for the low load lumbar flexion and extension exercise group in both angles (p<0.05) relative to controls. These data indicate that low load lumbar strength exercise training is an effective method of improving lumbar extension and flexion muscles strength.

1. Introduction

Anually the cost of medical care generated by low back pain is increasing and it has been estimated to be a major health problem in today's society. Low back pain is the most frequent cause of limitation of physical activity (Wing, 2001) or physical demanding work among people with age less than 45 years old (McCoy, Hadjipavlou, Overman, Necessary, & Wolf, 1997). However, the peak age for spine injuries is 40 years old (Andersson, Fine, & Silverstein, 1995).

The factors which may contribute to the risk of low back pain are the lack of sleep, fatigue, emotional instability, substance abuse (alcohol and drugs), smoking (Al-Obaidi, Anthony, Al-Shuwai, & Dean, 2004), family problems, overweight, physical inactivity, physical activity performed incorrectly (excessive or incorrect movements), weak muscle endurance, continous and very demanding physical activity at work, prolonged sitting, inaccurate chronic postures in orthostatic position, repeated backfall, flexion, twisting, pushing and/or lifting, prolonged driving vibrations, increased chronic stress (chronic stress is releasing cortisol hormone, which is involved in muscle and tendon injury), low job satisfaction, low motivation for work and mental fatigue (Bigos et al. 1992). It is also known that poor trunk muscle function may contribute to the risk of low back pain (Leino, Aro, & Hasan, 1987) in grater extent then structural disorders. So, a strong muscle corset around the lumbar spine could decrease the risk of low back pain or injury by increasing spine stability (Beim, Giraldo, Pincivero, Borror, & Fu, 1997).

Low back pain treatment is costly and frequently includes the use of special machines to train lower back muscles (Mafl, McCarthy, Davis, & London, 2013). Different forms of training exercises for the lumbar flexor and extensor muscles are of interest in rehabilitation programme, especially for low back pain patients.

Due to normal aging, body tissues can cause changes in the anatomy of the spine, especially in intervertebral disks. It is well known that most trunk strength exercises develop a compression of the lumbar spine between 1500N and 3000N (Axler & McGill 1997). Minimizing the lumbar compression is very important in selecting the most suitable trunk exercises to develop strength for seafarers with spine problems. So far, no strength exercise, performed at the spine was found to be optimal in developing muscle strength, and at the same time to provide a low (minimum) load on the intervertebral joints (Axler & McGill 1997).

Science, currently, cannot prescribe the best exercises to develop strength, for all problems encountered in the lumbar spine; the real possibility to diminish or to eliminate the problems encountered in the lumbar spine is the combination of scientific research with clinical experience in designing the optimal strength exercise programs. Thus, the selection process of lumbar low load strength exercises, applied in this study is based on safety or minimize the load at the level of lumbar spine and, also, on the optimal muscle actions necessary to develop lumbar muscle strength and endurance.

Therefore, the hypotesis of this investigation was to evaluate the low load lumbar flexion and extension exercise training on the development of isolated lumbar extension and flexion strength in healthy asymptomatic seafarers.

2. Material and methods

This longitudinal study was conducted in Constanta. After the presentation of study aims and methods, fifty-four healthy sedentary men (ordinary seamen all assigned on bulk earners and all present on land when this study was conducted), who had no history of chronic lumbar pain and no orthopedic or cardiovascular contraindications, volunteered for this investigation. Twentyseven of these subjects (mean age 337 ± 43 (years months)) were assigned to a low load lumbar flexion and extension training group and 27 (mean age 353 ± 37 (years months)) acted as controls and did not train. Characteristics of subjects by groups are shown in table 1. Written informed consent was obtained from all subjects.

Testing

Before and after 8 weeks training period, eact subjects completed an isometric strength test on DAVID F130 Lumbar/Thoracic Flexion machine (figure 1) (DAVID Fitness & Medical Ltd., Karitie 9, 01530 Vantaa, Finland) and DAVID FI 10 Lumbar/Thoracic Extension machine (figure 2). Each test included measurement of maximal voluntary isometric strength of the lumbar flexor and extensor muscles at 0° and 30°. Maximal voluntary lumbar isometric strength values were recorded on MC-3 microcomputer (figure 3), which was connected on each DAVID machine.

Subjects were seated in both machines with their knees positioned so that the femurs were parallel to the seat, with lower limbs secured in place by two restraints used to stabilize the pelvis. The lower limbs restraints consisted in two 90° pads on an adjustable crank, placed against the anterior side of the tibia and the femur covering the knee articulation, and a lap belt, for thigh restraint, that was secured in place over the top of the femurs, just below the waist. These restraints were forcing the pelvis back against a specially designed pelvic restraint. The combination of these restraining forces stabilized the pelvis, allowing no lateral, vertical or rotational movement.

Subjects were instructed not to exercise for at least 24 hours before testing. To initiate the test on David F 110 Lumbar/Thoracic Extension machine, subjects were first locked in 30° of flexion and instructed to slowly and continuously extent their back against the upper back pad (monement arm of machine) for 2 to 3 second period, with arms hanging relaxed. Once maximal tension had been achived, subjects were instructed to maintain the contraction for an additional 1 to 2 seconds before relaxing. A 60 second rest interval was provided until the next isometric contraction, while the 0° angle of measurement was set. The same protocol was maintained for David F130 Lumbar/Thoracic Flexion machine, with the remark that, the subjects slowly and continuously flex their spine against the upper chest pads for 2 to 3 second period, and standardized positioning of the arms was achived by two handle bars attached to an extending 30cm from the chest pads.

During the contractions, subjects were verbally encouraged to give a maximum effort. Lower limbs restraints were tightened if pelvic movement was observed during testing, to ensure pelvic stabilization.

Training

Twenty-seven subjects trained 3 days per week for 8 weeks and 27 served as controls and did not train the lumbar extensor and flexor muscles. Low load lumbar flexion and extension exercises were performed, with small exceptions, in the same days of the week, with one, respectively, two days of rest. Each training session had approximately 1 hour and 30 minutes. Training volume individualization was set, in accordance with maximal lumbar isometric strength values obtained in initial testing, for each subject.

Lumbar flexion and extension exercises were choosen to improve muscular endurance and strength through active movements (Vera-Garcia, Grenier, & McGill, 2000), presenting as a resistance factor, gravity and the weight of different body segments, and in the same time presenting the lowest intervertebral disc compression (fig. 4-7) (McGill, 1998).

Lumbar flexion and extension strength exercises were performed through repeated dynamic contractions and in a controlled manner; this kind of contraction presents eficiency in developing muscle peak power (Fitts, McDonald, & Schlüter, 1991), muscular strength for sedentary subjects (beginners) (Zaflorski, 1980) and, also, in rehabilitation strength programmes (Graves et al., 1990; Malosoux, Francaux, Nielens, & Theisen, 2006).

Data analisys

Isometric strength was measured in units of torque (Nm). Means and standard deviations were calculated for each angle of measurement. Between pretraining and postraining tests and, respectively, 0° and 30° flexion, comparisons were made using two-tailed dependent student t test. Between groups comparisons were made using two-tailed independent student t test. Statistical significance was accepted at p<0.05 (Lieber, 1990).

3. Results and discussions

Between pretraining and posttraining tests experiment group showed significant improvements of isometric strength, in both angles tested, for flexion (t=17.414 for 0° and t= 15.35 for 30°) and for extension (t=l 7.456 for 0° and 18.843 for 30°). Some improvements in isometric strength has showed, but in much lesser extent, in control group at 30° for both flexion (t=3.525) and extension (t=2.176). For flexion the best values of isometric strength has been recorded at 0° for both experiment group (pretraining t=29,372 and posttraining t=29,093) and control group (pretraining t=25,256 and posttraining t=l6.699). In contrast, for extension, the best values of isometric strength has been recorded at 30° for both experiment group (pretraining t=51,174 and posttraining t=49,205) and control group (pretraining t=64,698 and posttraining t=63,876).

The values of lumbar extension isometric strength were significantly higher in 30° of flexion and the values of lumbar flexion isometric strength were significantly higher in 0° of flexion. The pretraining and posttraining values of lumbar extension isometric strength were significantly higher in both angles (0° and 30° of flexion) than the values of lumbar flexion isometric strength, in both groups tested (table 2). Most studies showed that lumbar extension strength is clearly greatest in full flexion showing a linear descent from flexion to extension positions (Graves et ah, 1990) and is significantly higher than abdominal strength, in all angles of flexion tested (Straton & Cismaç, 2009).

Results comparing the pretraining and posttraining maximal isometric flexion and extension strength indicate that low load lumbar flexion and extension exercise training was effective for lumbar flexor and extensor muscles (table 2). Subjects, from the low load lumbar flexion and extension exercise training group, showed gains in maximal isometric extension strength of 5% (0° flexion) and 4.3% (30° flexion) and in maximal isometric flexion strength of 5.6% (0° flexion) and 4.5% (30° flexion).

Pollock et al. (1989), reported an increase in lumbar isometric strength, in mixed genders, from 102% (0° flexion) to 42% (72° flexion) after 10 weeks of training (one training session per week) on a MedX lumbar extension machine (Pollock et al., 1989). Graves et al. (1994), reported an increase in dynamic exercise loads, in mixed genders, of 29% in no stabilization of pelvis (NOSTAB) group and 39% in pelvic stabilization (P-STAB) group, after 12 weeks of training (one training session per week, one set of 8 to 12 repetitions to volitional exhaustion) on Nautilus lower back machine and Cybex Eagle back extension machine (NO-STAB) and, respectively, MedX lumbar extension machine (P-STAB) (Graves et ah, 1994).

In training, pelvic stabilization is not required to develop lumbar extension strength (Mayer, Graves, Udermann, & Ploutz-Snyder, 2002). However, it seems that isolated lumbar extension exercises are very effective in reducing low back pain in chronic patients, relative to identical exercises with no pelvic stabilization (Smith, Bissell, Bruce-Low, & Wakefield, 2011). Other studies showed that, variable resistance dynamic exercises provide an effective training stimulus for the development of lumbar extension strength (Tucci et al., 1992).

Trunk extension movements are accomplished by compound of lumbarpelvic rhythm, during normal daily activities when the pelvis is not stabilized. Lumbar flexion and extension exercises with no pelvic stabilization may not be an effective way to train for the specific industrial tasks and activities of daily living. Compared with resistance exercise training with or without pelvic stabilization realized on special machines, low load flexion and extension exercise training presented in this study, was much lower in efficiency. Even if lumbar extension movements without pelvic stabilization primarily exercise the hip extensor (gluteal and hamstring) muscles (Petersen, Amundsen, & Schendel, 1987), lumbar extensor muscles have some potential in developing strength.

However, resistive exercise training with pelvic stabilization, which effectively improve dynamic trunk flexion and extension strength, may not be an option for seafarers lumbar strength training when working on sea, because of the lack of pelvic stabilization machines presence on bulk carriers and because of the time spent on sea without strength training on pelvic stabilization machines, which it can be four to six months for ordinary seamen. Therefore, low load lumbar flexion and extension exercise training is an alternative method of developing lumbar strength for seafarers (including seafarers with history of low back pain), when working on bulk carriers.

4. Conclusions

Exercising 3 times per week, for 8 weeks with low load lumbar flexion and extension exercises increase the strength of the lumbar flexion and extension muscles, which confirm the study hypotesis.

These data have practical applications for seafarers which work on bulk carriers and, in the same time, participate in training programs for the lumbar spine.

Further research is necessary to determine the optimal frequency and/or duration of training, with low load flexion and extension strength exercises, necessary to produce the greatest improvement in lumbar flexion and extension strength for seafarers, with or without low back pain.

References

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Straton Alexandru 1 *

Micu Alexandru 2

Gidu Diana 3

Rata Marínela 4

1 Maritime University of Constanta, Mircea cel Bàtrân, no. 104, 900663 Constanta, Romania;

2,3 Ovidius University of Constanta, Blvd. Mamaia, no. 124, 900527 Constanta, Romania.

4 Vasile Alecsandri University of Bacau, Calea Märäsesti, nr. 157, Bacäu, 600115, Romania

* E-mail: [email protected]

INFLUENJA ANTRENAMENTULUI CU EXERCIJII CU INCARCARE SCÂZUTÂÎN DEZVOLTAREA IZOLATÄ A MUÇCHILOR FLEXORI §1 EXTENSORI LOMBARI LA PERSONALUL NAVIGANT DIN MARINA COMERCIALÄ

Cuvinte cheie: marinar, personal navigant, lombar, flexor, extensor, izometric, incärcare scäzutä, exercifu.

Rezumat

Scopul acestui studiu a fost sä evalueze antrcnamentul bazat pe bazat pe exercijii cu mcärcäturä redusä pentru muçchii lombari, flexori §i extensori, în dezvoltarea izolatä a forjei. Forja izometricä izolatä la nivelul muçchilor flexori çi extensori a fost mäsuratä în douä pozijii pe 54 de barbaji sänäto§i, înainte çi dupâ 8 säptämäni de antrenament bazat pe exercijii cu mcärcäturä redusä pentru muçchii flexori §i extensori lombari. Subiecjii au fost împârjiji în douä grupuri, primul grup (27) a fost antrenat de 3 ori/säptämänä cu exercijii cu mcärcäturä redusä iar cea de a doua grupä (control, 27) nu s-a antrenat. Valorile forjei izometrice indicä o îmbunâtâjire a forjei izolate la muschii flexori §i extensori lombari la subiecpi grupei de experiment la ambele unghiuri fafí de subiecpi grupului de control. Aceste date indicä faptul cä antrenamentul bazat exercipi eu mcärcäturä redusä pentru muçchii flexori §i extensori lombari reprezintä o metodä eficientä in dezvoltarea for|ei musculare lombare.

1. Introducere

Costurile anuale medícale generate de durerile lombare de spate sunt în creçtere çi sunt considerate a ft o problemä majorä de sänätate în societatea modernä. Durerile lombare de spate reprezintä cauza principalä de limitare a activitäpi fizice (Wing, 2001) sau a muncilor solicitante fizic în rândul oamenilor eu vârsta mai micä de 45 ani (McCoy, Hadjipavlou, Overman, Necessary, & Wolf, 1997). Oricum, värful afecpunilor coloanei vertebrale este atins la vârsta de 40 de ani (Andersson, Fine, & Silverstein, 1995).

Factorii care pot contribui la creçterea riscului de aparipe a durerilor lombare de spate sunt: lipsa somnului, extenuare, instabilitate emoponalä, abuz de anumite substance (alcool §i droguri), fumatul (Al-Obaidi, Anthony, AlShuwai, & Dean, 2004), problemele familiale, supraponderalitatea, inactivitatea fizicä, activitatea fizicä efectuatä incorect (miscäri inorecte sau excesive), rezisten|ä muscularä slabä, o activitate continuä çi intensä la locul de muncä, statul pe scaun în exces, pozipi cronice alterate în ortostatism, cäderi repetate pe spate, flexii, räsuciri, împingeri sau/§i ridicäri, vibrapi în timpul conducerii prelungite ale automobilelor, stress cronic märit (stresul cronic este légat de hormonul cortizon, care este implicat ín accidéntele la nivelul muçchilor §i tendoanelor), satisfacpe scäzutä la locul de muncä, motivare slabä pentru muncä §i activitäp fizice (Bigos et al. 1992). Este de asemenea cunoscut cä funcponarea precarä a musculaturii trunchiuiui poate contribui la creçterea riscului de dureri lombare de spate (Leino, Aro, & Hasan, 1987) într-o mäsurä mai mare în tulburäri structurale. Deci un corset muscular puternic la nivelul coloanei lombare poate descreste riscul durerilor §i accidentärilor musculare lombare prin creçterea stabilitätii coloanei vertebrale (Beim, Giraldo, Pincivero, Borror, & Fu, 1997).

Tratamentul durerilor lombare de spate este scump §i frecvent include folosirea unor aparate spéciale care sä antreneze musculatura lombarä a spatelui (Mafi, McCarthy, Davis, & London, 2013).Sunt folosite diferite forme de exercipi fizice pentru antrenarea muçchilor flexori §i extensori în prográmele de recuperare în special pentru pacienpi cu dureri lombare de spate.

Datoritä înaintârii normale în vârstâ (esuturile pot suferi schimbäri în anatomía coloanei vertebrale mai aies la nivelul discurilor intervertébrale. Este de notorietate cä majoritatea exercipilor pentru dezvoltarea musculaturii spatelui creazâ o compresie a coloanei lombare între 1500N §i 3000N (Axler & McGill 1997). Scäderea la mimim a compresiei stä la baza selecponärii celor mai bune exercitii pentru musculatura spatelui pentru personalul navigant cu problème la coloana vertebralä. Pânâ acum nu au fost gäsite exercipile musculare care aplícate coloanei vertebrale sä ofere o dezvoltare optimä a forfei çi în acela§i timp sä ofere o încârcare minimä asupra discurilor intervertebrale (Axler & McGill 1997).

Çtiinta, în acest moment, nu poate prescrie cel mai bun program de antrenament pentru dezvoltarea forfei, pentru tóate problemele întâlnite la coloanâ în regiunea lombarä; cea mai bunâ posibilitate este sä diminueze sau sä elimine problemele întâlnite la nivelul coloanei lombare în combinape eu cercetarea çtiinpficâ §i eu experienfa clinicä în proiectarea unui program optim de dezvoltare a forfei. De§i procesul de selectare a exercipilor eu încârcare redusä aplícate în acest studiu se concentreazä pe sigurantâ sau pe reducerea la minim a încârcârii coloanei vertebrale la nivel lombar §i de asemenea pe aepunile optime ale muçchilor necesare pentru dezvoltarea forfei çi rezistenfei la nivelul lombar.

Prin urmare, ipoteza acestui studiu va évalua sistemul de antrenament eu exercitii eu încârcare redusä pentru dezvoltarea izolatä a fortei muschilor flexori si extensori lombari la subiectii sänätosi care fac parte din personalul navigant al marinei comerciale.

2. Material si metode

Acest studiu a avut loe în Constanza. Dupä prezentarea scopului §i obiectivelor studiului §i a metodelor 54 de barbap sänätosi, sedentari (marinari obiçnuip, top îmbarcap pe nave vrachier çi top aflap pe uscat pe timpul acestui studiu), care nu au avut înregistrate dureri cornice lombare, çi nici contraindicapi ortopcdice sau cardiovasculare, s-au oferit voluntan pentru aceastä cercetare. Douäzeci §i çapte dintre subieep (media de vârstâ 337± 43 (ani luni))au fost înscriçi în grupa care a urmat programul de pregätire bazat pe exercipi eu încârcare redusä pentru muçchii flexori §i extensori lombari, ceilalp 27 eu media de vârstâ 353 ± 37 (ani lum)) au format grupa de control §i nu au urmat niciun antrenament. Caracteristicile subiecplor pe grupe sunt prezentate în tabelul 1. Subiecpi §i-au dat acordul scris privind participarea la acest studiu.

Testarea

Inainte §i dupä perioada de antrenament de 8 sâptâmâni flecare subiect a fost testât pentru determinarea fortei izometrice pe aparatul DAVID F130 Masina de flexie lombarä-toracicä (fig. 1) (DAVID Fitness & Medical Ltd., Karitie 9, 01530 Vantaa, Finland) §i pe aparatul DAVID FI 10 Maçina de extensie lombarä-toracicä (fig. 2). Fiecare test a inclus mäsurarea maximä voluntará a forjei izometrice a mu§chilor flexori çi extensori la unghiurile de 0° §i 30°. Valorile foifei izometrice voluntare au fost înregistrate de microcomputerul MC-3 (fig. 3), care a fost conectat la flecare dintre apáratele DAVID.

Subiecjii au stat a§ezaji pe cele douá aparate cu genunchii astfel a§ezaji încât femurul sä fíe paralel cu scaunul, cu membrele inferiore prinse de douá tampoane opritoare folosite pentru stabilizarea pelvisului. Opritoarele membrelor inferioare au fost douá tampoane dispuse la 90° pe o §iná reglabilá, plasate ín partea anterioará a tibiei §i femurului acoperind articulaba genunchiului, §i o centurä transversalá, de rejinere a coapsei, care este fíxeazá pe partea de sus a femurului, chiar mai jos de talie. Aceste opritoare forjeazá bazinul înapoi împotriva unui opritor special conceput. Combinaba acestor forje imobilizatoare au stabilizat pelvisul, nepermijând nici o mineare lateralá, verticalä sau de rotajie.

Subiecjii au fost instruiji sä nu facá exercijii fízice cel pujin 24 de ore ínainte de testare. Pentru a inijia testul pe aparatul David F 110 Extensie toracicá/lombará, subiectii au fost fixaji pentru prima datá la 30° de flexie çi instruiji sä execute încet çi continuu extensia contra tamponului din spate pentru perioadá 2-3 secunde, cu brajele reláxate. Dupá ce s-a atins nivelul maxim de íncordare subiecjii au fost instruiji §á menjiná contraeJi a pentru íncá 1-2 secunde supl imentare ínainte de relaxare. Un interval de 60 secunde de odihná a fost lásat páná la urmátoarea contracjie izometricá, ín timp ce a fost réglât unghiul de 0o.

Acelaçi protocol a fost aplicat pentru aparatul David F130 flexie-extensie toracicá/lombará, cu observajia cá, subiecjii au flexat coloana încet çi continuu împotriva tamponului superioar pentru piept pentru o perioadá de 2-3 secunde, pozijia standard a brajelor a fost realizatá cu ajutorul a douá mânere ata§ate la 30cm de la tampoanele pentru piept.

In timpul contracjiei subeicjii au fost íncurajaji verbal pentru a da maximul de efort. Membrele inferioare au fost fixate pentru a limita miçcarea pelvisului ín timpul testárii.

Antrenarea

Douäzeci §i §apte de subiecçi s-au antrenat trei zile pe säptämänä, timp dc 8 saptamani si 27 au servit drept grup de control §i nu si-au antrenat muschii zonei lombare. S-au efectuat exercitii de extindere lombarä, cu mici excepÇii, în aceleaçi zile ale säptämänii, cu una, respectiv, douä zile de repaus.

Fiecare sesiune de antrenament a durât aproximativ 1 ora si 30 minute. Intensitatea antrenamentului a fost stabilitä individual, ín conformitate cu valorile maxime de rezistenÇâ izometricä lombarä obçinute în testarea iniçialâ, pentru flecare subiect.

ExerciÇiile lombare de flexie §i extensie au fost álese pentru a imbunatâçi rezistenÇâ muscularä çi força, prin miçcâri active (VerA-GarciA, Grenier, & McGill, 2000), prezentând ca factor de rezistenÇâ, gravitaçia §i greutatea diferitelor segmente ale corpului, §i în acelaçi timp oferind cel mai scäzut grad de compresie la nivelul discurilor intervertebrale (fig. 4 -7) (McGill, 1998).

Exercitii de forÇâ la nivel lombar de tip flexie §i extensie au fost efectúate prin intermediul contracÇiilor dinamice repetate §i într-o maniera controlatä; acest tip de contracÇie prezintä eficienÇâ în dezvoltarea forÇei musculare de vârf (Fitts, McDonald, & Schlüter, 1991), forta muscularä pentru subiectii sedentari (începâtori) (ZaÇiorski, 1980) çi, de asemenea, în prográmele de forÇâ de recuperare (Graves et al., 1990; Malosoux, Francaux, NielenS, Theisen, 2006).

Analiza datelor

Puterea izometricä a fost mäsuratä in unitäfl de cuplu (Nm). Mediile §i deviaflile standard au fost calculate pentru flecare unghi de mäsurare. Intre testele anterioare antrenamentului §i testele post antrenament §i respectiv, 0° §i 30° flexie, comparapile au fost realízate utilizând douä grupe de eçantioane dependente prin testul t.

Intre grupuri comparapile au fost realízate eu ajutorul a douä teste t independente. Semniflcapa statisticä a fost stabilitâ la p <0.05 (Lieber, 1990).

3. Rezultate si discutii

Intre testele pre-antrenament çi post-antrenament grupul experiment a aratat imbunatatiri semnificative de fopä izometricä, în ambele unghiuri testate, pentru flexie (t = 17,414 de 0° çi t = 15,35 de 30°) §i pentru extensie (t = 17,456 de 0° §i 18,843 pentru 30°).

Unele hnbunätäpri în puterea izometricä a arätat, dar în mult mai micä mäsurä, grupul de control la 30° pentru ambele, flexie (t = 3,525) §i extensie (t = 2,176). Pentru flexie cele mai bune valori de fopä izometricä au fost inregistrate la 0°, atât pentru grupul experiment (pre-antrenament t = 29,372 §i postantrenament t = 29,093) §i grupul de control (t = 25,256 pre-antrenament §i postantrenament t = 16,699). în schimb, pentru extensie, cele mai bune valori de putere izometricä au fost înregistrate la 30° pentru ambele grupuri de experiment (pre-antrenament t = 51,174 §i post-antrenament t = 49205) §i de control (preantrenament t = 64,698 §i post-antrenament t = 63,876).

Valorile foflei izometrice a extensiei lombare au fost semnificativ mai mari la 30 ° de flexie, iar valorile pentru flexia lombarä au fost semnificativ mai mari la 0° de flexie. Valorile pre-antrenament çi post-antrenament de extindere lombarä la fofla izometricä au fost semnificativ mai mari la ambele unghiuri (0° si 30° de flexie) decât valorile de flexie lombarä la rezistenta izometricä, în ambele grupuri testate (tabelul 2).

Cele mai multe studii au aratat ca força de extensie lombarà este în mod ciar mai mare în flexie prezentând o scädere liniarâ faÇâ de extensie (Graves et al., 1990) si este semnificativ mai mare decât puterea abdominala, în tóate unghiurile de flexie testate (Straton & Cismaç. 2009).

Rezultatele compárate între pre-antrenament §i post-antrenament pentru flexie çi extensie maximalä izometricä în ceea ce priveste força indicä faptul câ flexia lombarä çi antrenamentul de extensie au fost eficiente pentru flexia lombarä §i mu§chii extensori (tabclul 2).

Subiectii, din grupul care a exécutât exercitii de flexie lombarä §i extindere, au arätat câçtiguri în força de extensie maximä izometricä de 5% (0 ° flexie) §i 4,3% (30 ° flexie) §i în força maximä de flexie izometricä de 5,6% (0 ° flexie ) çi 4,5% (30 ° flexie). Pollock et al., (1989), au raportat o crestere a forÇei izometrice lombarä, pe genuri mixte, de la 102% (0° flexie) la 42% (72° flexie) dupä 10 säptämäni de antrenament (o sesiune de instruire pc säptämänä) MEDX prelungire lombarä (Pollock et al., 1989).

Graves §i colab., (1994), au raportat o crestere a sarcinii de exerciçiu dinamic, pe genuri mixte, de 29% farä stabilizarea pelvisului (NO-STAB) si 39% in stabilizare pelvianä (P-STAB), dupä 12 säptämäni de antrenament (o sesiune de instruire pe säptämänä, un set de 8-12 repetäri pânâ la epuizare) pe Nautilus ce lucreazä zona de jos a spatelui §i Cybex Eagle ce lucreazä extensia spatelui (NO-STAB) §i, respectiv, MEDX pentru extensii lombare (P-STAB ) (Graves et al., 1994).

în antrenament, stabilizarea pelvianä nu este necesarâ pentru a dezvolta forta lombarä (Mayer, Graves, Udermann, Ploutz-Snyder, 2002). Cu tóate acestea, se pare câ exerciçiile de extensie lombarä sunt foarte eficiente în reducerea durerilor de spate la pacientii cronici, comparativ cu exerciçii identice farä stabilizare pelvinä (Smith, Bissell, Bruce-Low, & Wakefield, 2011). Alte studii au arätat cä, exerciçiile dinamice pot oferi força variabilâ la un stimul eficient prin antrenament pentru dezvoltarea forÇei lombare (Tucci et al., 1992).

Miçcârile de extensie aie trunchiului sunt realizate prin compus de ritm lombar-pelvian, în timpul activitâçilor zilnice normale, atunci când bazinul nu este stabilizat. Exercitiile de flexie §i extensie lombarä farä stabilizare pelviana nu pot fi o modalitate eficientä de antrenament pentru sarcinile specifice în activitâçile cotidiene.

Comparativ eu exercitii de forÇâ eu sau farä stabilizare pelvianä realizate pe aparate spéciale, exerciçiile de flexie §i extensie eu încârcare redusâ prezentate în acest studiu, au fost semnificativ mai ineficiente. Chiar daeâ miçcârile de extensie lombarä farä stabilizare pelvianä solicitä în primul rând extensorul soldului, muschii (Petersen, Amundsen, & Schendel, 1987), (fesier §i tendoanele genunchiului), muschii extensori lombari au un anumit potenÇial în dezvoltarea forÇei.

Cu tóate acestea, antrenamentul de forÇâ eu stabilizare pelvianä, care îmbunâtâÇeste în mod eficient flexia dinamicä a trunchiului §i puterea de extensie, nu poate fi o opçiune pentru navigatori atunci când se lucreazä pe mare, din cauza lipsei aparatelor de stabilizare pe vrachiere §i din cauza timpului petrecut pe mare, farä aparate de stabilizare pelvianä, care poate fi de patru pänä la §ase luni pentru marinarii obi§nuifi.

Prin urmare, antrenamentul bazat pe exercitii eu încârcare redusä pentru flexia çi extensia lombarä poate fi o metodä alternativä de dezvoltare a puterii lombare pentru navigatori (inclusiv navigatori cu antecedente de dureri lombare), atunci cänd lucreazä pe vrachiere.

4. Concluzii

Antrenamentul de 3 ori pe säptämänä, timp de 8 säptämäni, bazat pe exercifii de flexie §i extensie lombarä eu încârcare redusä poate creçte puterea de flexie §i extensie lombarä a muschilor.

Aceste date au aplicafii practice pentru navigatori care lucreazä pe vrachiere çi, în acelaçi timp, participä la programe de antrenament flzic la nivelul coloanei vertebrale lombare.

Cercetäri suplimentare sunt necesare pentru a determina frecvenfa optimä §i/sau durata antrenamentului bazat pe exercifii de flexie §i extensie lombarä cu încârcare redusä, necesare pentru a produce cea mai mare imbunatatire a forfei de flexie §i extensie lombarä pentru navigatori, cu sau farä dureri de spate.

Straton Alexandru 1

Micu Alexandru 2

Gidu Diana 3

Rata Marínela 4

1 Universitatea Marítima "Mircea cel Bâtrân" din Constanta, no. 104, 900663 Romania

2,3 Universitatea "Ovidius" din Constanta,, Blvd. Mamaia, no. 124, 900527 Romania

4 Universitatea "Vasile Alecsandri" din Bacäu, Calea Märasesti, nr. 157, 600115, Romania