📚 Year 8 Cambridge PE: Quick Reference Formulas & Principles | 剑桥八年级体育：公式定理速查手册
This quick reference handbook brings together all the essential formulas, principles and calculation shortcuts you will encounter in the Year 8 Cambridge Physical Education course. From heart rate zones and BMI to lever mechanics and one‑rep max estimation, these tools help you analyse performance, plan training and understand how your body responds to exercise. Keep this guide handy for revision, practical lessons and coursework.
本速查手册汇集了剑桥八年级体育课程中所有必备的公式、原理与计算速解法。从心率区间、身体质量指数到杠杆力学和一次最大重量估算，这些工具能帮助你分析运动表现、制定训练计划并理解身体对运动的反应。请保留本指南，方便复习、实践课和作业使用。
1. Maximum Heart Rate (MHR) | 最大心率
Your maximum heart rate is the highest number of beats per minute your heart can achieve during all‑out effort. It is primarily determined by age and provides the baseline for setting training intensities.
最大心率是你的心脏在全力运动时每分钟所能达到的最高心跳次数。它主要由年龄决定，并为设定训练强度提供基准。
MHR = 220 - age (in years)
linear formula is widely used in Cambridge PE to estimate MHR for young athletes. For a 13‑year‑old, MHR ≈ 220 - 13 = 207 bpm.
尽管个体间存在差异，但这一线性公式在剑桥体育中被广泛用于估算青少年运动员的最大心率。以13岁学生为例，MHR ≈ 220 − 13 = 207 次/分。
2. Target Heart Rate Zone | 靶心率区间
Training in specific heart rate zones ensures you develop the correct energy systems. The aerobic zone improves cardiovascular endurance, while higher intensities build anaerobic capacity.
在特定心率区间内训练能确保你锻炼到正确的供能系统。有氧区间提升心肺耐力，而更高强度则发展无氧能力。
Lower limit = MHR × 0.60
Upper limit = MHR × 0.80
For general fitness, aim for 60–80% of MHR. Using the example MHR of 207 bpm, the target zone is roughly 124–166 bpm. Some sprint‑based activities may require 80–90% of MHR.
一般体能训练的目标是最大心率的60%–80%。按上述207 bpm的MHR计算，靶心率区间约为124–166 bpm。某些冲刺类活动可能需要达到MHR的80%–90%。
3. Body Mass Index (BMI) | 身体质量指数
BMI is a simple screening tool that relates body weight to height. It helps categorise individuals into underweight, healthy weight, overweight or obese, though it does not distinguish between muscle and fat.
BMI是一种将体重与身高关联的简易筛查工具，用于划分体重过轻、健康体重、超重或肥胖，但它无法区分肌肉与脂肪。
BMI = weight (kg) ÷ [height (m)]²
of 50 ÷ (1.60 × 1.60) = 19.5 kg/m², which falls within the healthy range for adolescents.
一名体重50千克、身高1.60米的八年级学生BMI为 50 ÷ (1.60 × 1.60) = 19.5 kg/m²，属于青少年健康范围。
4. Speed Calculation | 速度计算
Speed is a fundamental component of physical fitness, measuring how quickly an athlete can move from one point to another. It is the basis for sprint times, game performance and many fitness tests.
速度是体能的基本组成部分，衡量运动员从一点移动到另一点的快慢。它是短跑成绩、比赛表现及众多体能测试的基础。
Speed = distance ÷ time
6 m/s. In Cambridge PE, you may also record time for a fixed distance and compare results.
若一名运动员8.5秒跑完60米，平均速度 = 60 ÷ 8.5 ≈ 7.06米/秒。在剑桥体育中，你还可能记录固定距离所用的时间并比较结果。
5. Work, Power and the Force‑Velocity Link | 功、功率与力‑速度关系
Understanding work and power helps explain why some movements are more demanding. Work is done when a force moves an object, and power measures how quickly that work is performed.
理解功和功率有助于解释为何某些动作更具挑战性。力使物体移动时便做了功，而功率衡量做功的快慢。
Work = force × distance (in the direction of the force)
Power = work ÷ time
For cyclical activities like cycling or rowing, power can also be expressed as:
对于骑行或划船等循环运动，功率也可表示为：
Power = force × velocity
Applying a greater force at a higher speed increases power output. This principle underlies explosive events such as jumping and throwing.
用更大的力并以更高速度运动能增加功率输出。这一原理是跳跃、投掷等爆发性项目的基础。
6. Mechanical Advantage in Levers | 杠杆的机械效益
Most human movements involve lever systems where bones act as levers and joints as fulcrums. Mechanical advantage tells you whether a lever multiplies force or speed.
人体大多数运动都涉及杠杆系统，骨为杠杆，关节为支点。机械效益表明杠杆是增力还是增速。
Mechanical Advantage = effort arm ÷ resistance arm
An advantage greater than 1 means less effort is needed to move a larger resistance (force multiplier). An advantage less than 1 favours speed and range of motion, as seen in the elbow during a basketball free throw.
机械效益大于1表示用较小的力就能移动较大的阻力（省力杠杆）。小于1则有利于速度和活动范围，如篮球罚球时的肘关节运动。
7. Training Volume Load | 训练负荷量
Monitoring training volume helps you track progress and avoid overtraining. Volume load combines sets, repetitions and load into a single number useful for resistance training.
监控训练量有助于追踪进步并避免过度训练。负荷量将组数、次数与重量合并为单一数值，对力量训练非常实用。
Volume load = sets × repetitions × weight (kg)
= 600 kg. Gradually increasing volume load applies the principle of progressive overload.
例如，用20千克完成3组、每组10次深蹲，负荷量为 3 × 10 × 20 = 600 千克。逐步增加负荷量正是渐进超负荷原则的体现。
8. Energy Expenditure Using METs | 以代谢当量估算能量消耗
MET (Metabolic Equivalent of Task) expresses the energy cost of an activity. One MET is approximately the resting energy expenditure of 3.5 ml of oxygen per kilogram per minute.
MET（代谢当量）表示活动的能量消耗。1 MET约等于每公斤体重每分钟消耗3.5毫升氧气的静息能耗。
1 MET = 3.5 ml O₂/kg/min
Energy (kcal) = METs × body weight (kg) × time (hours)
l. This formula links directly to discussions about energy balance and healthy lifestyles.
一名50千克的学生以4 METs快走30分钟（0.5小时）约消耗 4 × 50 × 0.5 = 100千卡。该公式与能量平衡和健康生活方式的话题直接相关。
9. Hydration Guidelines Formula | 补水指南公式
Proper fluid intake before, during and after exercise is essential for performance and safety. Cambridge PE uses body‑mass‑based formulas as a starting point for personal hydration plans.
运动前、中、后合理补充液体对表现和安全至关重要。剑桥体育以基于体重的公式作为个人补水计划的起点。
Pre‑exercise: 5–7 ml per kg of body weight, 2–3 hours before
During exercise: 150–350 ml every 15–20 minutes
Post‑exercise: 1.5 litres of fluid for every 1 kg of body weight lost
These figures are adjusted for heat, intensity and individual sweat rates. Recording pre‑ and post‑exercise body weight helps you calculate exact fluid replacement needs.
这些数值可根据温度、强度和个人出汗率加以调整。记录运动前后的体重有助于精确计算补液量。
10. Estimated One‑Rep Maximum (1RM) | 估算一次最大重量
A true 1RM test requires maximal effort which may not be safe for young adolescents. The Epley formula allows you to estimate 1RM from sub‑maximal repetitions, making it suitable for Year 8 strength monitoring.
真正的一次最大重量测试需要全力负荷，对青少年可能不安全。Epley公式允许通过次最大重复次数来估算1RM，适合八年级力量监测。
1RM ≈ weight × (1 + repetitions ÷ 30)
(1 + 8/30) = 30 × 1.267 ≈ 38.0 kg. Always prioritise safe technique over maximum loading.
如果一名学生能推举30千克8次，估算1RM = 30 × (1 + 8/30) = 30 × 1.267 ≈ 38.0千克。务必始终将安全技术放在比最大负荷更优先的位置。
11. FITT Principle Overview | FITT 原则概览
The FITT principle is a foundational framework for designing any training programme. It ensures all variables are considered to bring about adaptation safely.
FITT原则是设计任何训练计划的基础框架，它确保所有变量都得到考虑，从而安全地引发适应。
Frequency – how often you train
Intensity – how hard you work
Time – duration of each session
Type – the mode of activity
For aerobic endurance, a Year 8 programme might recommend Frequency of 3–4 times per week, Intensity at 60–80% MHR, Time of 30 minutes and Type such as continuous running or swimming. Adjusting one factor at a time allows structured overload.
对于有氧耐力，八年级计划可能建议频率每周3–4次，强度为60%–80% MHR，时间30分钟，类型为持续跑或游泳。每次调整一个因素可实现结构化的超负荷。
12. Training Intensity by Rate of Perceived Exertion (RPE) | 主观疲劳量表强度公式
When heart rate monitors are not available, the Rate of Perceived Exertion provides a practical way to gauge intensity. Combined with heart rate, it offers a cross‑check.
当没有心率监测设备时，主观疲劳量表提供了一种实用的强度评估方法。与心率结合使用，可进行交叉校验。
Estimated Heart Rate ≈ RPE × 10
On the 6–20 Borg scale, an RPE of 12 suggests a heart rate around 120 bpm. On the simplified 0–10 scale, multiplying by 10 gives a rough percentage of MHR, useful for quick in‑lesson adjustments.
在6–20博格量表中，RPE为12意味着心率大约在120 bpm。在简化的0–10量表中，RPE乘以10可大致表示MHR的百分比，便于课堂中快速调整强度。
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