{"id":2273,"date":"2022-07-18T17:20:48","date_gmt":"2022-07-18T15:20:48","guid":{"rendered":"https:\/\/www.btsbioengineering.com\/importance-of-muscular-pre-activation-times-during-evaluation-of-anterior-cruciate-ligament-acl-injury-risk-prevention\/"},"modified":"2025-03-20T10:38:05","modified_gmt":"2025-03-20T09:38:05","slug":"importance-of-muscular-pre-activation-times-during-evaluation-of-anterior-cruciate-ligament-acl-injury-risk-prevention","status":"publish","type":"post","link":"https:\/\/www.btsbioengineering.com\/it\/importance-of-muscular-pre-activation-times-during-evaluation-of-anterior-cruciate-ligament-acl-injury-risk-prevention\/","title":{"rendered":"Importance of muscular pre-activation times during evaluation of anterior cruciate ligament (ACL) injury risk prevention"},"content":{"rendered":"

ACL injuries<\/strong>\u00a0are\u00a0very common<\/strong>\u00a0in amateur\u00a0athletes\u00a0<\/strong>as well as in professionals, specifically football players. This accident\u00a0commonly occurs<\/strong>\u00a0during\u00a0changes of direction<\/strong>,\u00a0landing phase\u00a0<\/strong>and\u00a0after jumping<\/strong>, causing\u00a0heavy consequences<\/strong>\u00a0to athletes\u2019 sports life.\u00a0 It requires a prolonged period of absence from competition and an appropriate rehabilitation plan.\u00a0\u00a0<\/strong><\/p>\n

Even though\u00a070% of players<\/strong>, after the accident,\u00a0comes back\u00a0<\/strong>to the field (RTP) [2],\u00a0only two-thirds<\/strong>\u00a0of them\u00a0recover pre-injury levels<\/strong>\u00a0and with a high risk of relapse.<\/p>\n

So far, a few prospective\u00a0studies<\/strong>\u00a0have\u00a0investigated<\/strong>\u00a0the\u00a0biomechanical risk factors of ACL injury\u00a0<\/strong>[1]. MAROTTA et Al. [2] have shown that\u00a0the evaluation of activation timing during drop fall\u00a0<\/strong>test allows for\u00a0identifying the athletes at ACL injury risk<\/strong>.<\/p>\n

This allows\u00a0a previous identification of the subjects at risk<\/strong>\u00a0and introduces an\u00a0adequate training program\u00a0<\/strong>aiming at decreasing the risk.<\/p>\n

In the\u00a0drop fall test<\/strong>\u00a0four\u00a0EMG probes\u00a0<\/strong>are\u00a0placed<\/strong>\u00a0on the subject\u00a0on the following<\/strong>\u00a0right or left\u00a0limb muscles<\/strong>:
\n\u2013 Rectus Femoris
\n\u2013 Vastus Medialis
\n\u2013 Biceps Femoris
\n\u2013 Semitendinosus.<\/p>\n

Noninvasive\u00a0surface electrodes<\/strong>\u00a0are\u00a0placed superficially on the belly of the muscle<\/strong>, along the direction of the muscle fiber. An\u00a0inertial sensor<\/strong>\u00a0is also placed at sacrum level (S1) using a special belt.<\/p>\n

Once the\u00a0sensors have been positioned<\/strong>, the test can start:\u00a0the subject climbs onto a 30cm box<\/strong>\u00a0with a leading leg to be assessed;\u00a0then, he falls from the box<\/strong>\u00a0landing on the same leg.
\nSurface electromyography (sEMG)<\/strong>\u00a0and the\u00a0inertial sensor<\/strong>\u00a0allows for an evaluation of the muscle pre-activation times (muscle activations immediately prior to ground impact). Muscle pre-activation times should fall within precise normal values detected in literature [3] (Table 1).<\/p>\n

\n\n\n\n\n\n\n\n
MUSCLE<\/td>\nMEN<\/td>\nWOMEN<\/td>\n<\/tr>\n
Rectus Femoris (RF)<\/td>\n551 \u2013 666<\/td>\n541 \u2013 699<\/td>\n<\/tr>\n
Vastus Medialis (VM)<\/td>\n148 \u2013 299<\/td>\n357 \u2013 459<\/td>\n<\/tr>\n
Biceps Femoris (BF)<\/td>\n58 \u2013 156<\/td>\n25- 130<\/td>\n<\/tr>\n
Semitendinosus (S)<\/td>\n58 \u2013 156<\/td>\n25 \u2013 130<\/td>\n<\/tr>\n<\/tbody>\n<\/table>
Table 1 \u2013 Neuromuscular pre-activation times of quadriceps and thigh posterior muscles before landing [3]\u00a0<\/figcaption><\/figure>\n

 <\/p>\n

DE SIRE et al. [4] suggest that\u00a0a decrease in the pre-activation times<\/strong>\u00a0of the VMs\u00a0<\/strong>leads to a worsening of the mid-lateral recruitment pattern of the quadriceps, increasing the dynamic knee valgus and increasing the load on the ACL [10,11].
\nA\u00a0decrease in the activation time of the semitendinosus\u00a0<\/strong>before contact could increase the time required for the lower limb stabilization before the onset of the anterior shear force [30]. Furthermore, a\u00a0correct pre-activation of the semitendinosus<\/strong>\u00a0could dynamically protect the integrity of the knee joint and surrounding structures [30]. In addition, remember that to dynamically stabilize the knee during the varus and valgus moment, the co-contraction\u00a0Quadriceps \u2013 Hamstring<\/strong>\u00a0definable through their ratio (Q: H)\u00a0is essential<\/strong>. An unbalanced Q: H ratio can contribute to higher knee abduction loads by increasing the strain on the ACL load.<\/p>\n

The\u00a0drop fall test\u00a0<\/strong>is\u00a0extremely important<\/strong>\u00a0in the\u00a0preventive and return to sport field<\/strong>, since, in case of altered muscle pre-activation times, it is possible to intervene with appropriate training plans. Neuromuscular rewarming has been shown to reduce the risk of anterior cruciate ligament (ACL) injury. In a recent 2021 study, De Sire et Al showed how neuromuscular warming can prevent the risk of improving the activation time of knee stabilizer muscles [4].
\nThe\u00a0rehabilitation plan<\/strong>\u00a0hypothesized by the authors provides the execution of the exercises listed in Table 2:<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Mobility Exercise (5min)<\/td>\n<\/tr>\n
Joint Mobility<\/td>\n<\/tr>\n
Dynamic stretching<\/td>\n<\/tr>\n
Agility drills (30s per exercise)<\/td>\n<\/tr>\n
Light Run<\/td>\n<\/tr>\n
Knee lift and heel kicks run<\/td>\n<\/tr>\n
Backward Running with sidesteps<\/td>\n<\/tr>\n
Parade sideway running with raised arms<\/td>\n<\/tr>\n
Carioca sideway crossover foot running<\/td>\n<\/tr>\n
Intermittent stops forward running<\/td>\n<\/tr>\n
Trunk rotations forward running<\/td>\n<\/tr>\n
Cutting movements<\/td>\n<\/tr>\n
Sprint run<\/td>\n<\/tr>\n
Balance Exercise (4min) or balance board<\/td>\n<\/tr>\n
Squats (with the ball on one or two legs)<\/td>\n<\/tr>\n
Pushing each other off balance (pair exercise)<\/td>\n<\/tr>\n
Single-limb dead lift<\/td>\n<\/tr>\n
Side-Steps with resistance band<\/td>\n<\/tr>\n
Strength and power exercise (5min)<\/td>\n<\/tr>\n
Squats (to 80\u00b0 of flexion)<\/td>\n<\/tr>\n
Bulgarian split squat<\/td>\n<\/tr>\n
Bounding strides<\/td>\n<\/tr>\n
\u201cNordic hamstring lowers\u201d<\/td>\n<\/tr>\n
Forward jumping<\/td>\n<\/tr>\n<\/tbody>\n<\/table>
Table 2 \u2013 Neuromuscular warm up exercises [4]\u00a0<\/figcaption><\/figure>\n

The\u00a0study conducted on 25 professional footballers<\/strong>\u00a0of the Italian Second League in December 2019\u00a0shows significant improvements in pre-activation times<\/strong>\u00a0following the training execution.<\/p>\n

In conclusion,\u00a0thanks to<\/strong>\u00a0the introduction of\u00a0a simple and quick preventive test<\/strong>, it is possible\u00a0to assess the presence of altered neuromuscular activations<\/strong>\u00a0that cause\u00a0an increased risk of ACL injury<\/strong>, allowing for evaluating appropriate training and \/ or recovery plans aimed at minimizing the risk. Today we have technological tools available which, in a simple way and with reduced costs and times, allow the aforementioned evaluation with a very high-cost benefit.<\/p>\n

Bibliography<\/strong><\/p>\n

[1] LEPP\u00c4NEN, Mari, et al. Stiff landings are associated with increased ACL injury risk in young female basketball and floorball players.\u202fThe American journal of sports medicine, 2017, 45.2: 386-393.<\/span><\/p>\n

[2] MAROTTA, Nicola, et al. Correlation between dynamic knee valgus and quadriceps activation time in female athletes.\u202fJournal of Physical Education and Sport, 2020, 20.5: 2508-2512.<\/span><\/p>\n

[3] MEDINA, Jennifer M., et al. Timing of neuromuscular activation of the quadriceps and hamstrings prior to landing in high school male athletes, female athletes, and female non-athletes.\u202fJournal of Electromyography and kinesiology, 2008, 18.4: 591-597.<\/span><\/p>\n

[4] DE SIRE, Alessandro, et al. Anterior Cruciate Ligament Injury Prevention Exercises: Could a Neuromuscular Warm-Up Improve Muscle Pre-Activation before a Soccer Game? A Proof-of-Principle Study on Professional Football Players.\u202fApplied Sciences, 2021, 11.11: 4958.<\/span><\/p>\n\r\n

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