Strength training is often overlooked by endurance athletes and coaches. That’s a shame given the real benefits that endurance athletes can gain from including strength training in their weekly schedule.
In this article we’ll take a look at the benefits of strength training for endurance, look at the positive effects it has on endurance exercise, and why strength training has that effect. We’ll look at which key factors (efficiency, lactate threshold) improve following strength training. And, look at what research tells us about how best to include strength training in our weekly training schedule.
The benefits of strength training for endurance athletes
Strength/resistance training has been demonstrated to have a positive impact on a number of endurance sports. These include endurance running, cycling, swimming, rowing, and cross country skiing.
Strength training is believed to have this positive effect by increasing the strength of individual muscle fibres – making each contraction more forceful and enhancing fatigue resistance. Strength training also impacts neuro-muscular co-ordination, increasing the speed and efficiency of muscular contractions and ultimately making you a more efficient athlete.
Research is clear that strength training has a positive impact on endurance exercise performance, and has demonstrated that it has a number of positive effects:
- Increased leg strength (Rønnestad et al., 2011; Losnegard et al., 2011; Marcinik et al., 1991; Hickson et al., 1988;)
- Maximal power (Yamamoto et al., 2010),
- The velocity at VO2max (Taipale et al., 2010),
- Supra-maximal (>VO2max) cycling performance (Minahan and Wood 2008),
- Short and long term endurance performance (Aagaard et al., 2011; Rønnestad et al., 2011; Yamamoto et al., 2010; Sato and Mokha 2009; Paavolainen et al., 1999b; Tanaka and Swensen 1998);
- Improves time to exhaustion in cyclists and runners (Støren et al., 2008; Minahan and Wood 2008; Marcinik et al., 1991),
- Improves exercise efficiency (Louis et al., 2012; Mikkola et al., 2011; Sunde et al., 2010; Paavolainen et al., 1999b;)
- Leads to improvements in blood lactate levels and the lactate threshold (Paton and Hopkins 2005; Marcinik et al., 1991).
How does strength training improve endurance performance?
Strength training is believed to improve endurance exercise performance in a number of ways.
At the most basic level we know that strength training leads to an increase in the size, strength and fatigue resistance of muscle fibres. Research has also shown that strength training can lead to neuromuscular improvements (Mikola et al., 2007). We also see an increase in the proportion of Type IIa muscle fibres (fast oxidative-glycolytic fibers – these have greater fatigue resistance than type IIb) whilst there’s an associated decrease in the proportion of the much less fatigue resistant Type IIb muscle fibres (Aagaard et al., 2011). A further adaptation is an increase in the muscle cross sectional area.
These physiological adaptations lead to improvements in some of the key factors related to endurance exercise performance.
In particular, we see improvements in exercise efficiency, we see an increase in the lactate threshold, and improved fatigue resistance. Most of these improvements appear to be related to improved neuromuscular coordination, increased strength and muscle fibre type transitions, from less to more fatigue resistant muscle fibre types.
Importantly, these adaptations often occur in endurance athletes without any significant increases in bodyweight (Rønnestad et al., 2010a), and through an increase in the proportion of energy from aerobic energy systems (Minahan and Wood 2008).
Strength Training and Exercise Efficiency
One area where strength training really benefits endurance is through improved exercise efficiency. Exercise efficiency relates to the energy cost of exercise. When we talk about improved efficiency we are talking about a reduced energy cost of exercise. This can be assessed as the energy cost (kj) or oxygen consumption.
Here, we have seen improved efficiency in runners, cyclists, swimmers and cross country skiiers.
Strength training and running efficiency
Both resistance and explosive strength training have been shown to significant improve running economy (Cheng et al., 2012; Mikkola et al., 2011; Taipale et al., 2010; Guglielmo et al., 2009; Yamamoto et al., 2008; Spurrs et al., 2003; Millet et al., 2002; Paavolainen et al., 1999b).
In one study researchers found that explosive strength training, consisting of sprint training and jumping exercises (including bilateral countermovement, drop and hurdle jumps), significantly improved running economy by more than 8% (Paavolainen et al., 1999b). In another study, 6-weeks of Plyometric training improved both running economy and 3km running performance (Spurrs et al., 2003).
The improvements in running economy, following plyometric training, are believed to be due in part to increased lower leg musculotendinous stiffness. The increased stiffness is believed to improve joint stability and enhance the energy return during the footstrike.
Heavy resistance training has also been found to significantly increase running economy (5-6%) (Guglielmo et al., 2009; Støren et al., 2008;). The optimum level of resistance training is not clear, however, research suggests that explosive, heavy resistance training and strength endurance resistance training can all lead to significant improvements in running economy (Mikkola et al., 2011).
Research also suggests that whole body vibration training can lead to significant improvements in running economy (Cheng et al., 2012). However, circuit training appears to be less effective at improving running economy (Taipale et al., 2010).
Strength training and cycling efficiency
Resistance training – particularly explosive training and high resistance training – has also been found to be beneficial for improving cycling economy (Louis et al., 2012; Rønnestad, et al., 2012; Sunde et al., 2010; Paton and Hopkins 2005; Loveless et al., 2005;).
In one study researchers found that the addition of explosive strength training, and high-resistance interval training, to the training programs of well-trained cyclists led to major gains in sprint and endurance performance. The improvements were attributed in part to improved exercise efficiency (Paton and Hopkins 2005).
Strength training has also proved beneficial to master endurance cyclists. In one study, researchers got master age group cyclist (51.5 ± 5.5 years) to complete 10 sets of 10 knee extensions (70% of repetition maximum, with 3min rest between sets). This was found to alleviate the age related reductions in both strength and cycling efficiency (Louis et al., 2012).
The positive effects of resistance training on cycling economy have led researchers to suggest that cyclist include maximal strength training as part of their training routine (Sunde et al., 2010).
Strength training and swimming efficiency
There is limited research with regard to strength training and highly technical sports like swimming.
Early research failed to find improvements in swim stroke dynamics following a resistance training programme (Tannaka et al., 1993) – demonstrating the importance of specificity of resistance training in technical sports like swimming. However, research has found that dry-land strength training improved stroke length in national level swimmers (Girold et al., 2012).
Resisted sprint swim training has also been found to be beneficial for improved stroke technique in swimming (Girold et al., 2006). Arms only swim training (consisting of 20% of weekly training volume) – a training technique that increases the work done by arms at a given speed when swimming – also appears to be beneficial for swimming movement economy (Konstantaki et al., 2008).
Strength training and cross country skiing
Strength training and the Lactate Threshold
Early research highlighted that strength training may be an effective means of increasing the lactate threshold (Tanaka and Swensen 1998; Marcinik et al, 1991;).
A combination of explosive and high resistance interval training has been shown to improve exercise efficiency and the anaerobic threshold in a group of well-trained cyclists (Paton and Hopkins 2005). It is believed that the improvements in the lactate/anaerobic threshold occur due to a combination of improved exercise efficiency/economy, increased muscle fibre-recruitment during exercise and an increase in the proportion of energy from aerobic metabolism.
1. Improved exercise efficiency – when we see improvements in exercise efficiency we often see improvements in a range of speeds/intensities – from low intensity, right up to near maximal intensities. In this was any improvement in exercise efficiency can push up/increase the lactate threshold speed, or power.
2. Improved strength of individual muscle fibres – another possible reason for the improvement in the lactate threshold relates to the improved strength of individual muscle fibres. This reduces the overall work performed by individual muscle fibres at a given intensity. This allows a greater amount of work to be performed before reaching the point of the lactate threshold.
3. Increased proportion of energy from aerobic metabolism – any increase in the proportion of energy from aerobic metabolism will mean the transition from mainly aerobic to increased anaerobic metabolism occurs at higher exercise intensities. In turn this pushes up the lactate threshold speed, or intensity.
Strength Training and improved endurance exercise performance
So how does strength training impact endurance exercise performance? A number of studies have found improved endurance exercise performance, and fatigue resistance, following resistance training (Aagaard et al., 2011; Mikkola et al., 2011; Rønnestad et al., 2010a & 2011; Yamamoto et al., 2010; Sato and Mokha 2009; Paton and Hopkins, 2005; Hoff et al., 2002;).
First, lets take a look at strength training and cycling performance.
Strength training and endurance cycling performance
Strength training has been shown to improve endurance cycling in both long term, and short term events. Not surprisingly, supra-maximal (above VO2max) intensity cycling has also been found to improve following strength training.
Research looking at the effects of combined endurance and strength/resistance training on time trial performance in young top-level cyclists found significant improvements in both short (5min) and long (45min) time trial performance (Aagaard et al., 2011). The improvements were accompanied by an increase in type IIa muscle fibres and a decrease in type IIx fibres.
Research in well-trained cyclists has also found that heavy resistance training can improve performance in a 5minute all-out effort, following a 185 minute cycle (Rønnestad et al., 2011).
Strength training can also be used in a competition period, in order to maintain and enhance gains in strength and performance, from a previous preparatory period of training. (Rønnestad et al., 2010).
Strength training has also been found to improve supramaximal cycling performance (Minahan and Wood 2008). Interestingly this study found that the increase in time to exhaustion at 120% VO2peak was associated with increased aerobic energy contribution rather than increased anaerobic capacity.
Strength training and endurance running performance
A range of different resistance training methods and intensities have been found to be effective at enhancing endurance running performance:
1) Heavy resistance training has been shown to improve the time to exhaustion at the maximal aerobic running speed in well trained long distance runners (Støren et al., 2008);
2) Explosive strength training improved 5km race performance (Paavolainen et al., 1999b);
3) Running specific strength training has been found to help minimize the reductions in stride length that can occur as fatigue sets in. (Esteve-Lanao et al., 2008); and
4) Core strength training has been shown to improve 5000m run times after just six weeks of training (Sato and Mokha 2009).
What is the best type of strength training for endurance athletes?
To date there have been numerous studies highlighting the benefits of explosive strength training (Saunders et al., 2006; Paton and Hopkins 2005; Spurrs et al., 2003; Paavolainen et al., 1999b), heavy resistance training (Louis et al., 2012; Aagaard et al., 2011; Rønnestad et al., 2011 & 2010a; Mikkola et al., 2011; Losnegard et al., 2011; Sunde et al., 2010; Guglielmo et al., 2009; Minahan and Wood, 2008; Støren et al., 2008; Loveless et al., 2005; Hoff et al., 2002 & 1999); vibration plate training (Cheng et al., 2012) and core strength training (Sato and Mokha 2009) for improving endurance performance.
Whilst we know that strength training is definitely beneficial for endurance athletes, it is not clear which method provides the greatest benefit, for endurance athletes. As an example, one study found that explosive strength training improved running economy to a greater extent than dynamic weight training (Berryman et al., 2010;), whilst another found that heavy weight training appeared to be better at improving running economy than explosive strength training (Guglielmo et al., 2009).
What we can say is that strength training is beneficial. And, it is likely that a combination of heavy weight training and explosive/plyometric training may provide the best approach to improve endurance performance. However, it is important to remember that there is a greater risk of injury with plyometric training and it should not be undertaken by anyone without an adequate strength/resistance training background.
It’s important to consider the strength training background of an endurance athlete before undertaking any heavy weight training programme. Research in rowers found that less experienced rowers experienced greater gains through the use of high repetition numbers than experienced rowers (Ebben et al., 2004), suggesting that endurance athletes should aim to gradually increase the resistance training intensity in line with their level of experience.
Endurance athletes that are new to resistance training should start using light/moderate weights and employ a high repetition approach. Endurance athletes with a greater level of strength training experience, and greater level of adaptation, can place a greater emphasis on heavier weights and less repetitions.
Research also suggests that it may not be necessary for athletes to perform the repetitions to failure (Izquierdo-Gabarren et al., 2010) and therefore you should use a weight that allows you to achieve the target rep range across all sets.
What's the optimum number of repetitions, sets and frequency of strength training for endurance athletes?
Traditionally, it has always been viewed that the best approach for endurance athletes is to complete sets of approximately 15-20 repetitions with a weight that is approximately 60-65% of 1 repetition maximum (Martin and Coe, 1997). However, most current research looking at the benefits of strength training on endurance performance has utilised heavier weights with a lower repetition range (4-10reps at approximately 70-85% 1RM).
Athletes who are new to strength training should start with lighter weights and utilise higher repetition numbers (e.g. 15-20 reps) and gradually increase the intensity (% of RM) e.g. Weeks 1-4 = 15-20RM, Weeks 5-8 = 12-15RM, Weeks 9-12 = 10-12RM, Weeks 13-16 = 8-10RM. This is important as it allows muscles and tendons to strengthen and adapt to the weight in a progressive manner.
2. Optimum number of strength training sets for endurance athletes
Most of the research has used 3-10 sets during their research. If you are performing more than one exercise during the workout then 3 sets per exercise tends to work well e.g. 3 sets of half squat, 3 sets of leg extension, and 3 sets of leg curl.
3. Strength training frequency for endurance athletes
All the current research has used a training frequency of 2-3 times per week. Two times per week is likely to be adequate particularly if you are also including high intensity interval training. Consider varying the intensity on different days e.g. strength training day 1 train at an intensity of 5-6RM, strength training day 2 train at an intensity of 8-10RM – this periodized approach has been shown to produce greater gains than the traditional approach of always training within the same repetition range.
Summary of strength training approaches used in research
The table below details the training approaches (repetitions, sets, repetition maximum – RM, and training frequency) used during research looking at strength training.
|Louis et al., (2012)||10 x 10 knee extensions (70% 1RM)||3 x Weekly||Cyclists|
|Rønnestad et al., (2012)||4 lower body exercises, 3 × 4-10 RM||2 x Weekly||Cyclists|
|Rønnestad et al., (2011)||4 lower body exercises, 3 × 4-10 RM||2 x Weekly||Cyclists|
|Rønnestad et al., (2010a)||4 lower body exercises, 3 × 4-10 RM||2 x Weekly||Cyclists|
|Rønnestad et al., (2010)||4 lower body exercises, 3 × 4-10 RM||2 x Weekly||Cyclists|
|Sunde et al., (2010)||4 x 4 RM Half Squats||3 x Weekly||Cyclists|
|Minahan and Wood (2008)||4 x 5 reps at 85% 1RM||3 x Weekly||Cyclists|
|Støren et al., (2008)||4 x 4 RM||3 x Weekly||Runners|
|Saunders et al., (2006)||30 minute plyometric session||3 x Weekly||Runners|
|Paavolainen et al., (1999)||15-90 minutes of Explosive Training||32% of Training Volume||Runners|
|Hoff et al., (2002)||3 x 6 RM (85% of 1RM)||3 x Weekly||XC Skiing|
Summary of Strength Training for Endurance
- Strength training has been shown to be a beneficial training technique for a number of endurance sports including cycling, running, swimming, rowing, and cross country skiing.
- Concurrent strength and endurance training has been shown to increase the size and fatigue resistance of muscle-fibres as well as increasing the proportion of type IIa and decreasing the proportion of the less fatigue resistant type IIb fibres.
- Strength training has been shown to significantly enhance exercise efficiency, improve the speed or power output at the lactate threshold, increase fatigue resistance and improve exercise performance.
- There are four types of strength training that have been demonstrated to enhance exercise performance: heavy resistance training, explosive strength training, core strength training and vibration plate training. Of the four types heavy resistance training and plyometric training are believed to be the most effective.
- Current research suggests training using weights that can be lifted for 4-10repetitions (approximately 70-85% of 1 repetition maximum). Each workout should consist of 3-10 sets and be completed 2-3 times per week.
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