故事
爆发力和弹跳,跳得更高靠什么
爆发力是在很短时间里把力量用出来的能力。这里讲神经和肌腱怎么帮你起跳、力量和跳跃训练各补哪一段、落地怎么护住膝盖,以及上了年纪为什么还要练。
最后更新:
先读这一段 爆发力不等于力量:它是力乘以速度,看的是在很短的时间里能用出多少力。
科普内容,不替代医师诊断或处方;有症状或在服药请咨询医师。
故事路径
第 1 章
爆发力和力量是一回事吗
Is power the same as strength?
爆发力不等于力量:它是力乘以速度,看的是在很短的时间里能用出多少力。 起跳时,从开始蹬地到离地只有零点几秒;一项超声研究分析的蹬伸阶段,是离地前最后约 350 毫秒,而在关节不动的用力测试里,肌肉要超过 300 毫秒才达到最大力量。所以最大力量是天花板,起跳那一下能用上多少,还要看力起得多快,这叫发力速度。
这一篇写给打篮球、排球,想跳得更高、跑得更快的人,也写给上了年纪的人:起身、迈步、差点摔倒时稳住,靠的同样是快速发力。
今天可以开始的一步:下次从椅子上站起或做深蹲时,往上的那一段尽量快,往下保持控制。
起跳或落地时脚踝后方或膝盖下方啪的一声,之后踮不起脚或伸不直膝盖,要警惕肌腱断裂,这是急症,要尽快就医;运动中胸痛、胸闷或晕倒,立即拨打急救电话,详见跳跃会不会伤到膝盖一章。
这一篇写给打篮球、排球,想跳得更高、跑得更快的人,也写给上了年纪的人:起身、迈步、差点摔倒时稳住,靠的同样是快速发力。
今天可以开始的一步:下次从椅子上站起或做深蹲时,往上的那一段尽量快,往下保持控制。
起跳或落地时脚踝后方或膝盖下方啪的一声,之后踮不起脚或伸不直膝盖,要警惕肌腱断裂,这是急症,要尽快就医;运动中胸痛、胸闷或晕倒,立即拨打急救电话,详见跳跃会不会伤到膝盖一章。
机制 · 起跳那一下来不来得及
发力速度(RFD)说的是肌肉开始收缩之后,力往上升得有多快。Aagaard 2002 写道,它决定了收缩最初 0–200 毫秒里能产生多少力。Maffiuletti 2016 的综述补充说,收缩最初 300 毫秒里的快速起力,对运动员要紧,对需要在突然失去平衡时稳住自己的老人也一样要紧。起跳正好落在这个时间窗里。Kurokawa 2001 用超声观察 8 名男性原地起跳,分析的蹬伸阶段是离地前最后约 350 毫秒;而在关节不动的用力测试里,肌肉要超过 300 毫秒才能达到最大力量。按这两个数推,起跳结束时,肌肉多半还没来得及用出全部力量;这是推论,不是同一项研究直接测出来的。
这就是力量大的人不一定跳得高的原因:最大力量决定上限,发力速度决定这一下能用到上限的多少。两者也不是互不相干:Aagaard 2002 里,15 名男性练了 14 周大重量力量训练,最大力量从 291.1 牛·米升到 339.0 牛·米,收缩最初 200 毫秒里的发力速度也一起提高了。这项研究没有另设不训练的对照组。
第 2 章
神经怎么让肌肉更快发力
How nerves make muscle fire faster
发力快不快,先看神经:最初几十毫秒里,它能一下子调动多少肌纤维、指令发得多密。 一根运动神经和它管的那一群肌纤维,合起来叫一个运动单位。Maffiuletti 2016 的综述总结说,发力速度主要取决于爆发收缩最初 50–75 毫秒里的神经激活,尤其是运动单位放电有多快。
这一部分练得出来。一项 1998 年只有 5 人的小研究里,受试者练了 12 周快速勾脚,肌肉本身的收缩时间没有变,变的是神经:运动单位启动得更早、最高放电频率更高,还多了间隔只有 2–5 毫秒的连发。大重量力量训练也能提高发力速度,同样主要靠神经激活得更快。这和刚开始练力量时,头几周变强主要靠神经是同一个道理(见 神经驱动 vs 肌纤维)。
今天可以开始的一步:做力量动作时,往上推的那一段尽可能快,往下放时保持控制。
这一部分练得出来。一项 1998 年只有 5 人的小研究里,受试者练了 12 周快速勾脚,肌肉本身的收缩时间没有变,变的是神经:运动单位启动得更早、最高放电频率更高,还多了间隔只有 2–5 毫秒的连发。大重量力量训练也能提高发力速度,同样主要靠神经激活得更快。这和刚开始练力量时,头几周变强主要靠神经是同一个道理(见 神经驱动 vs 肌纤维)。
今天可以开始的一步:做力量动作时,往上推的那一段尽可能快,往下放时保持控制。
证据 · 练快速发力改变了什么
那项 1998 年的研究练的是小腿前面负责勾脚的肌肉:负荷是最大力量的 30%–40%,每次都尽量快地勾起,共练 12 周。练完后,最大力量和快速收缩的速度都上去了;用电刺激测,肌肉单次收缩的时间进程没有变,所以作者认为速度的提高主要来自神经。在快速收缩里,运动单位启动得更早、最高放电频率更高,出现 2–5 毫秒连发的运动单位比例从 5.2% 升到 32.7%。只有 5 名受试者,也没有对照组,这是一项机制研究,不是效果试验。Aagaard 2002 测的是大重量力量训练:14 周后,收缩最初 200 毫秒里的肌电信号幅度升高了 22%–143%,作者认为发力速度的提高可以用神经驱动增强来解释。Maffiuletti 2016 的综述把两条线合在一起:爆发式训练和大重量力量训练都能提高发力速度,主要都是让肌肉更快被激活。
肌纤维类型也有关系:II 型纤维起力比 I 型快,而不同人肌肉里的纤维组成差别很大。这能解释一部分人与人之间的差别;上面两项研究里变化最明显的,是神经怎样调动这些纤维。
第 3 章
肌腱像弹簧一样帮你起跳
How the tendon works like a spring
起跳最后那一下,出力最猛的往往不是肌纤维,而是先被拉长、再弹回去的肌腱。 Kurokawa 2001 用超声看原地起跳时的小腿肌肉:离地前的大半段,肌纤维在缩短,把连着跟腱的肌腱拉长,存进弹性能量;最后约 100 毫秒,肌纤维几乎不再变短,整条肌肉和肌腱却在快速回缩,把存下的能量放出来,这一段的峰值功率比肌纤维自己出的还高。先拉长、再缩短的这种动作模式,叫拉长-缩短周期。
先下蹲再跳几乎总比蹲着停住再跳高,但一项研究和一篇综述都认为,主要原因是下蹲让肌肉在往上蹬之前就把力起好了,弹性能量只贡献一小部分。
肌腱会随负荷变硬、变结实,但节奏比肌肉慢:一篇 汇总的训练研究都至少 8 周(见 肌腱修复)。今天可以开始的一步:跳跃练习从幅度小、落地轻的开始,给肌腱留出跟上的时间。
先下蹲再跳几乎总比蹲着停住再跳高,但一项研究和一篇综述都认为,主要原因是下蹲让肌肉在往上蹬之前就把力起好了,弹性能量只贡献一小部分。
肌腱会随负荷变硬、变结实,但节奏比肌肉慢:一篇 汇总的训练研究都至少 8 周(见 肌腱修复)。今天可以开始的一步:跳跃练习从幅度小、落地轻的开始,给肌腱留出跟上的时间。
证据 · 先下蹲为什么跳得更高
Bobbert 1996 让 6 名男性排球运动员做两种跳:先下蹲马上起跳,和蹲到同样的位置停住再跳。即使蹬伸开始时的身体姿势一样,先下蹲的那种平均也高 3.4 厘米。作者用肌肉骨骼模型分析后认为,可以排除弹性能量的储存和再利用;下蹲的作用,是让肌肉在开始缩短之前就进入高度激活、把力起好,于是蹬伸的前半段能做更多的功。一篇 2017 年的综述得出相近的结论:两种跳的差别主要来自下蹲时肌肉的松弛被提前收紧、激活提前建立起来,弹性能量可能只有很小的贡献。这和上面那项超声研究并不矛盾。Kurokawa 2001 看的是蹲着直接起跳,问的是一次蹬伸里谁在出力,答案是肌腱的回弹在最后一段起作用;Bobbert 1996 问的是先下蹲为什么更高。两件事都在起跳里发生。
不同的训练练到的地方也不一样。Kubo 2007 让 10 名受试者一条腿做跳跃训练(单腿连续跳,和从台上落下马上弹起的跳深),另一条腿做大重量的小腿训练,练 12 周:大重量那条腿的肌腱变硬了,跳跃那条腿的肌腱没变,变的是落地缓冲时脚踝的刚度,而且三种跳的高度都提高得更多。作者认为,跳跃训练带来的进步来自肌肉和肌腱这套结构的力学性质,而不是肌肉激活方式的改变。
第 4 章
除了深蹲还要练什么
What to train besides squats
深蹲这类力量训练抬高天花板,跳跃训练练的是快速发力和弹性,两样补的是不同的一段。 跳跃训练也叫增强式训练,指连续跳、跳上箱子这类利用拉长-缩短周期的练习。一篇汇总 26 项研究的 里,健康人练跳跃之后,先下蹲再跳的高度平均提高 8.7%。
先补哪一段,看你缺哪一段。一项随机试验里,24 名力量偏弱的男性练 10 周:练大重量深蹲和练负重跳,跳跃功率提高得差不多,深蹲的最大重量却分别涨了 31.2% 和 4.5%。作者的结论是,力量偏弱的人先练力量更划算;综述也写道,没有相当的力量,就很难有很高的爆发力。练力量本身的门道,见 力量训练入门。
下面只是机制的例子,不是训练计划:深蹲、上台阶练力量;原地纵跳、跳上低箱、跳绳练快速发力。今天可以开始的一步:力量还弱、深蹲还不熟练,先把力量练起来;有了基础,再加一点跳跃练习。
先补哪一段,看你缺哪一段。一项随机试验里,24 名力量偏弱的男性练 10 周:练大重量深蹲和练负重跳,跳跃功率提高得差不多,深蹲的最大重量却分别涨了 31.2% 和 4.5%。作者的结论是,力量偏弱的人先练力量更划算;综述也写道,没有相当的力量,就很难有很高的爆发力。练力量本身的门道,见 力量训练入门。
下面只是机制的例子,不是训练计划:深蹲、上台阶练力量;原地纵跳、跳上低箱、跳绳练快速发力。今天可以开始的一步:力量还弱、深蹲还不熟练,先把力量练起来;有了基础,再加一点跳跃练习。
证据 · 练跳跃能让人跳高多少
Markovic 2007 汇总了随机和非随机的对照试验,对象是健康人。练跳跃之后,蹲着直接起跳的高度平均提高 4.7%,先下蹲再跳提高 8.7%,加上摆臂提高 7.5%,从台上落下马上弹起的跳深提高 4.7%;作者认为这些提高在统计上显著,在实践中也有意义。这个数要读准边界。Kons 2023 的伞形综述汇总了 29 篇跳跃训练的 ,结论是它能改善大多数相关的体能和运动表现指标;但只有 5 篇是和对照组比较的,其余 24 篇用的是练前练后的自身比较,所以作者提醒,结果要谨慎看待。
两种训练练到的部位也不一样。在 Kubo 2007 那项一条腿一种练法的研究里,大重量训练让肌腱变硬,跳跃高度只在蹲着直接起跳时提高了;跳跃训练没有让肌腱变硬,却提高了落地缓冲时脚踝的刚度,三种跳都跳得更高。
kons-2023-plyometric-umbrella-review
证据 · 先练力量还是先练跳
Cormie 2010 的受试者都能用标准动作深蹲,但力量偏弱。他们被随机分到三组:大重量深蹲(最大重量的 75%–90%)、全力负重跳(最大重量的 0%–30%),以及不练的对照组,练 10 周。两个训练组的跳跃和 40 米冲刺都进步了,组间差别不显著:跳跃峰值功率分别提高 17.7% 和 17.6%;但最大力量只在深蹲组大幅上涨。作者据此认为,对力量偏弱的人,力量训练在短期内换来的运动表现和爆发力训练差不多,长期还多了最大力量,所以更划算。Cormie 2011 的综述把这一条写成了原则:力量和爆发力之间有一个基本关系,没有相当的力量,就很难有很高的爆发力;在此之上,针对一个人最弱的那一环训练,进步最大。Suchomel 2016 汇总了 200 多项研究,结论是更大的力量和更好的跳跃、冲刺、变向能力相关,也和更低的受伤风险相关。
读准边界:Cormie 2010 只有 24 名男性、只练了 10 周;对已经很强壮的人该先练什么,这项研究回答不了。
suchomel-2016-importance-strength
第 5 章
跳跃会不会伤到膝盖
Does jumping hurt your knees?
跳跃会给膝盖下方和脚踝后方的肌腱加负荷,而负荷本身也是肌腱变结实的刺激;要防的是落地太硬,和跳的量加得比肌腱适应得快。 落地时,身体要在一瞬间刹住下落:一项随机试验里,从 30 厘米高的箱子跳下,落地冲击平均约为体重的 4.5 倍;教受试者落地时髋和膝一起弯、前脚掌先着地之后,降到约 3.6 倍。膝盖弯得更深的软着地冲击更小,更多能量由大腿和臀部的肌肉吸收。
膝盖和小腿之间的疼痛常和反复跑跳有关,俗称跳跃膝(见 膝盖痛)。一项年轻排球运动员的队列里,训练时间越长,得跳跃膝的风险越高;这是观察到的关联。
今天可以开始的一步:落地时让声音轻下来,髋和膝一起弯下去缓冲;跳的量慢慢加,一次只加一样。
起跳或落地时突然剧痛、啪的一声,之后踮不起脚、伸不直膝盖或摸到凹陷,要警惕肌腱断裂,这是急症,要尽快就医,别自己练。运动中胸痛、胸闷或晕倒,立即拨打急救电话。
膝盖和小腿之间的疼痛常和反复跑跳有关,俗称跳跃膝(见 膝盖痛)。一项年轻排球运动员的队列里,训练时间越长,得跳跃膝的风险越高;这是观察到的关联。
今天可以开始的一步:落地时让声音轻下来,髋和膝一起弯下去缓冲;跳的量慢慢加,一次只加一样。
起跳或落地时突然剧痛、啪的一声,之后踮不起脚、伸不直膝盖或摸到凹陷,要警惕肌腱断裂,这是急症,要尽快就医,别自己练。运动中胸痛、胸闷或晕倒,立即拨打急救电话。
证据 · 落地有多重,怎么变轻
Prapavessis 1999 让 91 名健康人从 30 厘米高的箱子跳下,尽量轻地落在测力台上。随机分到指导组的人,被提醒注意髋和膝的动作、用前脚掌先着地,落地的峰值冲击从体重的 4.53 倍降到 3.57 倍;只被要求凭第一次的感觉再轻一点的人,几乎没有变化(4.51 倍到 4.33 倍)。作者认为,过高的冲击可能是受伤的诱因之一。Devita 1992 比较了 8 名女运动员从 59 厘米高处落下时的软着地和硬着地:软着地时膝盖平均弯到 117 度,硬着地只有 77 度。硬着地的地面反作用力更大;软着地时,髋和膝的肌肉吸收了更多能量,硬着地时脚踝吸收得更多。
跳跃膝的那项研究是 Visnes 2013:141 名 16 到 18 岁的排球学生被跟踪 4 年,28 人得了跳跃膝。排球训练每多一小时,风险的是 1.72;男生的风险是女生的 3 到 4 倍。这是观察性研究,说明训练量和跳跃膝一起出现,不能单独证明是哪一下跳造成的。
孩子也可以练跳跃。一篇纳入 7 项研究的系统综述发现,5 到 14 岁的孩子练跳跃后,跑和跳的能力明显提高,在家长同意、孩子愿意、有安全规范的前提下是安全的;不过这 7 项研究的质量都偏低。孩子怎么按发育阶段练,见 青少年训练。
johnson-2011-plyometric-young-children
红旗 · 哪些信号要立刻停下就医
下面这些不是普通的酸痛,而是要立即处理的信号。本站不诊断,出现时先停下来。起跳或落地时突然一阵剧痛,听到或感到啪的一声,之后无法用力、踮不起脚,或者摸到一处凹陷:要警惕肌腱断裂(例如跟腱断裂),这是急症,要尽快就医,别自己练。膝盖受伤时听到啪的一声,之后膝盖发软、站不住或伸不直:可能是韧带、肌腱或半月板撕裂,尽快就医。运动中或运动后突发胸痛、胸闷,像被压住或攥紧,可能放射到手臂、脖子或下颌,伴气短、出冷汗:可能是心脏急症,立即拨打急救电话。在运动中晕倒:立即拨打急救电话。
膝盖和小腿之间反复疼、常在反复跑跳之后,可能是髌腱的问题,怎么调整负荷让它好起来,见 膝盖痛;几周还不见好,去看医生。
第 6 章
年纪大了还要练爆发力吗
Does power still matter with age?
要。爆发力随年龄掉得比力量更早、更快,而起身、上台阶、差点摔倒时稳住,靠的都是它。 一项横断面研究比较了 65 到 89 岁的健康人:年龄每大一岁,静力力量少 1%–2%,腿部爆发力少约 3.5%;按体重算的腿部爆发力,和从矮椅子站起的速度、能迈上的台阶高度都有关。一篇综述把爆发力列为预示老人行动受限的重要指标。神经也有一份:71 到 84 岁的人做快速勾脚,发力速度比年轻人慢 48%,运动单位放电慢 27%。
练爆发力不必跳。一篇汇总 20 项随机试验的 里,60 岁以上的健康老人做力量训练时把重量尽快举起、再慢慢放下,日常身体功能比普通力量训练多改善一点,证据确定性低。
今天可以开始的一步:从椅子上站起时尽量快,坐下时慢慢来。有已知心脏病,或用力时出现过胸痛、不明气短或晕厥,先找医生评估再开始。训练中或训练后突发胸痛、胸闷,或在运动中晕倒,立即拨打急救电话。
练爆发力不必跳。一篇汇总 20 项随机试验的 里,60 岁以上的健康老人做力量训练时把重量尽快举起、再慢慢放下,日常身体功能比普通力量训练多改善一点,证据确定性低。
今天可以开始的一步:从椅子上站起时尽量快,坐下时慢慢来。有已知心脏病,或用力时出现过胸痛、不明气短或晕厥,先找医生评估再开始。训练中或训练后突发胸痛、胸闷,或在运动中晕倒,立即拨打急救电话。
证据 · 老人练快速发力安全吗
Balachandran 2022 汇总了 20 项随机试验、566 名住在社区的健康老人(平均 70.1 岁,65% 是女性),比较两种力量训练:一种照常控制着举起和放下,另一种举起时尽可能快、放下时保持控制。13 项试验测了身体功能,快速举起的那一组多改善了一点(标准化均数差 0.30),证据确定性低;作者认为,还需要更大、质量更高的试验。安全方面,两组都没有报告严重不良事件;但 20 项试验里有 14 项没把不良事件报告完整,多数试验只有 12 周、样本也小,所以这句话的分量有限。这类研究里的快,是在力量训练里把举起的那一段做快,不是让老人去跳。
关于年龄的那组数字也要读准:Skelton 1994 是横断面比较,不是跟踪同一批人,每年少 3.5% 这样的数,是不同年龄的人之间的差别,而且只在男性里,爆发力下降得明显比力量快,在女性里差别没有达到统计显著。肌肉为什么随年龄流失、怎么用力量训练对抗它,见 老年抗阻训练。
参考文献 · 25
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- Maffiuletti, N. A., Aagaard, P., Blazevich, A. J., Folland, J., Tillin, N., & Duchateau, J. (2016). Rate of force development: physiological and methodological considerations. European Journal of Applied Physiology, 116(6), 1091-1116. Narrative review. Rate of force development '(1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50-75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way' (abstract, PMID 26941023). Full text (PMC4875063): a rapid rise in force in the initial phase of a voluntary contraction (0-300 ms) 'is vital not only to the trained athlete but also to the elderly individual who needs to counteract sudden perturbations in postural balance'; maximal torque in isometric contractions is reached only after more than 300 ms; the rate of tension development is faster in type II than type I fibres, and fibre type composition varies widely between individuals; older adults (71-84 years) showed a 48% slower RFD and a 27% lower motor unit discharge rate at the onset of ballistic ankle dorsiflexions than young adults (about 20 years). 10.1007/s00421-016-3346-6
- Aagaard, P., Simonsen, E. B., Andersen, J. L., Magnusson, P., & Dyhre-Poulsen, P. (2002). Increased rate of force development and neural drive of human skeletal muscle following resistance training. Journal of Applied Physiology, 93(4), 1318-1326. 'The maximal rate of rise in muscle force [rate of force development (RFD)] has important functional consequences as it determines the force that can be generated in the early phase of muscle contraction (0-200 ms).' 15 male subjects measured before and after 14 weeks of heavy-resistance strength training (38 sessions): maximal isometric quadriceps strength rose from 291.1 to 339.0 N·m; contractile RFD rose at 30, 50, 100 and 200 ms after contraction onset (for example from 1,601 to 2,020 N·m/s at 30 ms); normalized to MVC, RFD rose 15%; EMG amplitude rose 22-143% and rate of EMG rise 41-106% in the first 200 ms. Conclusion: 'increases in explosive muscle strength (contractile RFD and impulse) were observed after heavy-resistance strength training. These findings could be explained by an enhanced neural drive, as evidenced by marked increases in EMG signal amplitude and rate of EMG rise in the early phase of muscle contraction' (abstract, PMID 12235031). 10.1152/japplphysiol.00283.2002
- Balachandran, A. T., Steele, J., Angielczyk, D., Belio, M., Schoenfeld, B. J., Quiles, N., Askin, N., & Abou-Setta, A. M. (2022). Comparison of power training vs traditional strength training on physical function in older adults: a systematic review and meta-analysis. JAMA Network Open, 5(5), e2211623. 20 RCTs, 566 healthy community-living adults aged 60 or older (mean 70.1 years, 65% women), comparing power training (lifting weights fast and lowering under control) with traditional strength training. Power training was associated with better physical function in 13 RCTs (n = 383; SMD 0.30, 95% CI 0.05-0.54), low-certainty evidence. Full text (PMC9096601): 'There were no serious adverse events reported for either group'; adverse events were insufficiently reported in 14 of 20 RCTs; most trials were short (12 weeks) and small. Conclusion: 'PT was associated with a modest improvement in physical function compared with traditional strength training in healthy, community-living older adults. However, high-quality, larger RCTs are required to draw more definitive conclusions' (abstract, PMID 35544136). 10.1001/jamanetworkopen.2022.11623
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- NHS. (2023). Knee pain (page last reviewed 21 December 2023). Pain between the kneecap and shin, often caused by repetitive running or jumping, may be tendonitis. A knee that is unstable, gives way when you try to stand or cannot be straightened, perhaps with a popping sound during the injury, may be a torn ligament, tendon or meniscus or cartilage damage. Get advice from 111 now if the knee is very painful, you cannot move it or put any weight on it, it is badly swollen or has changed shape, it locks, gives way or painfully clicks, or you have a very high temperature with redness or heat around the knee. www.nhs.uk/symptoms/knee-pain
- NHS. (2026). Heart attack: symptoms. Symptoms can include chest pain that may feel like crushing or squeezing on the chest and may spread to the arm, neck and jaw; feeling short of breath; feeling or being sick; feeling like indigestion; sweating; and pale, blue or grey skin. Call 999 for chest pain that feels tight or like squeezing, or that spreads to the arms, neck or jaw, with severe difficulty breathing, or if someone becomes unresponsive. A heart attack needs emergency treatment in hospital (page last reviewed 31 March 2026). www.nhs.uk/conditions/heart-attack/symptoms
- NHS. (2026). Fainting (page last reviewed 17 August 2026). Fainting is when you pass out for a short time; it is not usually serious, but anyone who has fainted should see a GP to find out what might have caused it. Causes can include standing up too quickly (which could be a sign of low blood pressure), not eating or drinking enough, being too hot, being very upset or in severe pain, heart problems, and taking drugs or drinking too much alcohol. Call 999 if someone is not breathing, cannot be woken up within 1 minute, has not fully recovered or has difficulty with speech or movement, has chest pain or a pounding, fluttering or irregular heartbeat (palpitations), has seriously hurt themselves before or after fainting, is shaking or jerking (a seizure), fainted while exercising, or fainted while lying down; do not drive yourself to A&E. If you feel about to faint: lie down with your legs raised, or if you cannot, sit with your head lowered between your knees; drink some water; cross your legs while standing up or rock up and down on your toes; clench your fists. If you see someone faint: check whether they respond by gently shaking their shoulders and asking loudly; if not, shout for help and tilt back the head and lift the chin; listen for breathing for at least 10 seconds; if they are breathing normally, lay them on their back and raise their legs (on their side if pregnant, especially over 28 weeks); they usually wake up within 30 seconds. www.nhs.uk/conditions/fainting
- Van Cutsem, M., Duchateau, J., & Hainaut, K. (1998). Changes in single motor unit behaviour contribute to the increase in contraction speed after dynamic training in humans. The Journal of Physiology, 513 Pt 1, 295-305. Five subjects trained the ankle dorsiflexors for 12 weeks with fast dorsiflexions against 30-40% of maximal strength. Training raised maximal voluntary contraction and the speed of ballistic contraction; 'This last enhancement was mainly related to neural adaptations since the time course of the muscle twitch induced by electrical stimulation remained unaffected.' During ballistic contractions motor units 'were activated earlier and had a greater maximal firing frequency'; the share of sampled units firing brief 2-5 ms doublets rose from 5.2% to 32.7%. Conclusion: 'It is likely that earlier motor unit activation, extra doublets and enhanced maximal firing rate contribute to the increase in the speed of voluntary muscle contraction after dynamic training' (abstract, PMID 9782179). 10.1111/j.1469-7793.1998.295by.x
- Moritani, T., & deVries, H. A. (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. American Journal of Physical Medicine, 58(3), 115-130. A small training study, not a randomized trial: 7 young men and 8 women, 8 weeks of isotonic strength training. Neural factors accounted for the larger share of the initial strength gain; after the first 3 to 5 weeks hypertrophy became the dominant factor. The abstract gives no percentage split between neural and hypertrophic contributions (abstract, PMID 453338). pubmed.ncbi.nlm.nih.gov/453338
- Bobbert, M. F., Gerritsen, K. G., Litjens, M. C., & Van Soest, A. J. (1996). Why is countermovement jump height greater than squat jump height? Medicine & Science in Sports & Exercise, 28(11), 1402-1412. Six male volleyball players; even with the same body position at the start of push-off, countermovement jump height was on average 3.4 cm greater than squat jump height. 'The greater jump height in CMJ was attributed to the fact that the countermovement allowed the subjects to attain greater joint moments at the start of push-off.' 'According to simulation results, storage and reutilization of elastic energy could be ruled out as explanation for the enhancement of performance in CMJ over that in SJ. The crucial contribution of the countermovement seemed to be that it allowed the muscles to build up a high level of active state (fraction of attached cross-bridges) and force before the start of shortening, so that they were able to produce more work over the first part of their shortening distance' (abstract, PMID 8933491). 10.1097/00005768-199611000-00009
- Van Hooren, B., & Zolotarjova, J. (2017). The difference between countermovement and squat jump performances: a review of underlying mechanisms with practical applications. Journal of Strength and Conditioning Research, 31(7), 2011-2020. 'Countermovement jump performance is almost always better than SJ performance, and the difference in performance is thought to reflect an effective utilization of the stretch-shortening cycle.' Conclusion: 'the difference in performance may primarily be related to the greater uptake of muscle slack and the buildup of stimulation during the countermovement in a CMJ. Elastic energy may also have a small contribution to an enhanced CMJ performance. Therefore, a larger difference between the jumps is not necessarily a better indicator of high-intensity sports performance' (abstract, PMID 28640774). 10.1519/JSC.0000000000001913
- Bohm, S., Mersmann, F., & Arampatzis, A. (2015). Human tendon adaptation in response to mechanical loading: a systematic review and meta-analysis of exercise intervention studies on healthy adults. Sports Medicine - Open, 1(1), 7. 27 studies (37 interventions of at least 8 weeks, 264 healthy adults aged 18-50, Achilles or patellar tendon): stiffness SMD 0.70, Young's modulus SMD 0.69, cross-sectional area SMD 0.24, all significant. Stiffness adaptation depended on loading intensity but not on contraction type; 'Although not significantly different, SMD was higher for interventions with longer duration (≥12 weeks).' Conclusion: 'tendons are highly responsive to diverse loading regimens. However, the data strongly suggests that loading magnitude in particular plays a key role for tendon adaptation in contrast to muscle contraction type' (abstract, PMID 27747846). 10.1186/s40798-015-0009-9
- Magnusson, S. P., Langberg, H., & Kjaer, M. (2010). The pathogenesis of tendinopathy: balancing the response to loading. Nature Reviews Rheumatology, 6(5), 262-268. Mechanical loading upregulates collagen expression and synthesis in tendon: 'This increase in collagen formation peaks around 24 h after exercise and remains elevated for about 3 days. The degradation of collagen proteins also rises after exercise, but seems to peak earlier than the synthesis.' 'Despite the ability of tendons to adapt to loading, repetitive use often results in injuries, such as tendinopathy'; microrupture and material fatigue are suggested injury mechanisms, implying one or more weak links in the structure (abstract, PMID 20308995). 10.1038/nrrheum.2010.43
- Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., & Kjaer, M. (2013). Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C. The FASEB Journal, 27(5), 2074–2079. Bomb-pulse 14C in 28 forensic Achilles tendon core samples and 4 muscle samples: the tendon core retained 14C levels matching the atmosphere several decades before sampling, showing very limited tissue turnover, while muscle showed continuous turnover (abstract, PMID 23401563). 10.1096/fj.12-225599
- Markovic, G. (2007). Does plyometric training improve vertical jump height? A meta-analytical review. British Journal of Sports Medicine, 41(6), 349-355. Meta-analysis of randomised and non-randomised controlled trials in healthy individuals (26 studies). Pooled improvement in jump height with plyometric training: squat jump 4.7% (95% CI 1.8 to 7.6), countermovement jump 8.7% (7.0 to 10.4), countermovement jump with arm swing 7.5% (4.2 to 10.8), drop jump 4.7% (0.8 to 8.6); effect sizes 0.44, 0.88, 0.74 and 0.62. Conclusion: 'PT provides a statistically significant and practically relevant improvement in vertical jump height with the mean effect ranging from 4.7% (SJ and DJ), over 7.5% (CMJA) to 8.7% (CMJ). These results justify the application of PT for the purpose of development of vertical jump performance in healthy individuals' (abstract, PMID 17347316). 10.1136/bjsm.2007.035113
- Cormie, P., McGuigan, M. R., & Newton, R. U. (2010). Adaptations in athletic performance after ballistic power versus strength training. Medicine & Science in Sports & Exercise, 42(8), 1582-1598. Relatively weak men (n = 24) randomized to heavy strength training (back squats at 75-90% of 1RM), ballistic power training (maximal-effort jump squats at 0-30% of 1RM) or control, three sessions a week for 10 weeks. Jump and sprint performance improved in both training groups with no significant difference between them (jump peak power: strength 17.7%, power 17.6%; 40-m sprint: 2.2% and 3.6%); squat 1RM rose 31.2% with strength training versus 4.5% with power training. Conclusion: 'Improvements in athletic performance were similar in relatively weak individuals exposed to either ballistic power training or heavy strength training for 10 wk... The ability of strength training to render similar short-term improvements in athletic performance as ballistic power training, coupled with the potential long-term benefits of improved maximal strength, makes strength training a more effective training modality for relatively weak individuals' (abstract, PMID 20139780). 10.1249/MSS.0b013e3181d2013a
- Cormie, P., McGuigan, M. R., & Newton, R. U. (2011). Developing maximal neuromuscular power: part 2 - training considerations for improving maximal power production. Sports Medicine, 41(2), 125-146. Narrative review. 'First, a fundamental relationship exists between strength and power, which dictates that an individual cannot possess a high level of power without first being relatively strong. Thus, enhancing and maintaining maximal strength is essential when considering the long-term development of power.' 'Ballistic, plyometric and weightlifting exercises can be used effectively as primary exercises within a power training programme that enhances maximal power'; plyometric exercises should involve stretch rates and loads similar to the sport. 'A training programme that focuses on the least developed factor contributing to maximal power will prompt the greatest neuromuscular adaptations and therefore result in superior performance improvements for that individual' (abstract, PMID 21244105). 10.2165/11538500-000000000-00000
- Kubo, K., Morimoto, M., Komuro, T., Yata, H., Tsunoda, N., Kanehisa, H., & Fukunaga, T. (2007). Effects of plyometric and weight training on muscle-tendon complex and jump performance. Medicine & Science in Sports & Exercise, 39(10), 1801-1810. Ten subjects trained the plantar flexors for 12 weeks, plyometric training (hopping and drop jumps) on one leg and weight training (80% of 1RM) on the other. 'Tendon stiffness increased significantly for WT, but not for PT. Conversely, joint stiffness increased significantly for PT, but not for WT. Whereas PT increased significantly jump heights of SJ, CMJ, and DJ, WT increased SJ only. The relative increases in jump heights were significantly greater for PT than for WT'; muscle activation during jumping changed no differently between legs. Conclusion: 'the jump performance gains after plyometric training are attributed to changes in the mechanical properties of muscle-tendon complex, rather than to the muscle activation strategies' (abstract, PMID 17909408). 10.1249/mss.0b013e31813e630a
- Prapavessis, H., & McNair, P. J. (1999). Effects of instruction in jumping technique and experience jumping on ground reaction forces. Journal of Orthopaedic & Sports Physical Therapy, 29(6), 352-356. Randomized controlled trial in 91 non-impaired subjects who jumped from a 300 mm box and tried to land as softly as possible on a force plate. Those given instructions to focus on hip and knee joint motion and a forefoot landing reduced peak ground reaction force from 4.53 to 3.57 times body weight; those asked only to use the experience of their first jump did not (4.51 to 4.33). Conclusion: 'High ground reaction forces may be a precipitating factor associated with an injury, where the site of tissue damage would benefit from decreased forces. These findings support the use of instructions related to joint motion to reduce landing forces' (abstract, PMID 10370919). 10.2519/jospt.1999.29.6.352
- Devita, P., & Skelly, W. A. (1992). Effect of landing stiffness on joint kinetics and energetics in the lower extremity. Medicine & Science in Sports & Exercise, 24(1), 108-115. Eight female athletes landed from a 59 cm fall with soft (on average 117 degrees of knee flexion) and stiff (77 degrees) landings. 'The stiff landing had larger GRFs'; 'The hip and knee muscles absorbed more energy in the soft landing (hip, -0.60 vs -0.39 W.kg-1; knee, -0.89 vs -0.61 W.kg-1), while the ankle muscles absorbed more in the stiff landing (-0.88 vs -1.00 W.kg-1)' (abstract, truncated at 250 words, PMID 1548984). 10.1249/00005768-199201000-00018
- Visnes, H., & Bahr, R. (2013). Training volume and body composition as risk factors for developing jumper's knee among young elite volleyball players. Scandinavian Journal of Medicine & Science in Sports, 23(5), 607-613. Four-year prospective cohort of 141 healthy elite volleyball students aged 16-18; 28 developed jumper's knee. Boys had three to four times the risk of girls; volleyball training had an odds ratio of 1.72 (1.18-2.53) for every extra hour trained, and match exposure an odds ratio of 3.88 (1.80-8.40) for every extra set played per week; body composition did not differ. Conclusion: 'male gender, a high volume of volleyball training and match exposure were risk factors for developing jumper's knee' (abstract, PMID 22260424). 10.1111/j.1600-0838.2011.01430.x
- Skelton, D. A., Greig, C. A., Davies, J. M., & Young, A. (1994). Strength, power and related functional ability of healthy people aged 65-89 years. Age and Ageing, 23(5), 371-377. Cross-sectional study of 50 healthy men and 50 healthy women evenly spread across ages 65-89. 'The differences in isometric strength and leg extensor power over the age range were equivalent to losses of 1-2% per annum and approximately 3 1/2% per annum, respectively. The decline of explosive power was faster than the decline of knee extensor strength in men (p = 0.0001), but not significantly so in women (p = 0.08). Power standardized for body weight influenced chair rise time and step height' (abstract, PMID 7825481). 10.1093/ageing/23.5.371
- Reid, K. F., & Fielding, R. A. (2012). Skeletal muscle power: a critical determinant of physical functioning in older adults. Exercise and Sport Sciences Reviews, 40(1), 4-12. Review: 'Muscle power declines earlier and more precipitously with advancing age compared with muscle strength. Peak muscle power also has emerged as an important predictor of functional limitations in older adults.' The authors' working hypothesis is that lower extremity muscle power is 'a more discriminant variable for understanding the relationships between impairments, functional limitations, and resultant disability with aging' (abstract, PMID 22016147). 10.1097/JES.0b013e31823b5f13
- Riebe, D., Franklin, B. A., Thompson, P. D., Garber, C. E., Whitfield, G. P., Magal, M., & Pescatello, L. S. (2015). Updating ACSM's recommendations for exercise preparticipation health screening. Medicine & Science in Sports & Exercise, 47(11), 2473-2479. ACSM roundtable: 'there is considerable evidence that exercise is safe for most people and has many associated health and fitness benefits; exercise-related cardiovascular events are often preceded by warning signs/symptoms; and the cardiovascular risks associated with exercise lessen as individuals become more physically active/fit.' The new screening model rests on current activity level, the presence of signs or symptoms or known cardiovascular, metabolic or renal disease, and the desired exercise intensity (abstract, PMID 26473759). 10.1249/MSS.0000000000000664