SHORT COMMUNICATION

Heart rate response to a marathon cross-country skiing race:a case study

Damiano Formenti • Athos Trecroci •

Luca Cavaggioni • Andrea Caumo •

Giampietro Alberti

Received: 18 February 2014 / Accepted: 7 April 2014

� Springer-Verlag Italia 2014

Abstract The aim of this study was to assess the exercise

intensity during a ski marathon race by monitoring the

heart rate (HR) of a well-trained male amateur skier taking

part in La Sgambeda 2012 (42 km long). The race con-

sisted of a preliminary short lap of 3.5 km and two almost

identical laps of 19 and 19.5 km, respectively. The sub-

ject’s resting and maximal heart rates (HRrest and HRmax)

were 60 and 180 beats/min, respectively. During the race,

HR and altitude were recorded every 1 s using a HR

monitor with GPS system. To describe the exercise inten-

sity profile, three reference HRs were selected. The refer-

ence HRs were calculated from the ‘‘Karvonen formula’’

by multiplying the HR reserve (HRR; HRR = HRmax-

HRrest) by the factors 0.5, 0.7, 0.9 and adding these values

to HRrest. The HR profile was classified into four levels of

exercise intensity. The skier performed the race in 1 h

55 min 40 s, with an HRmean of 160 beats/min (89 % of

HRmax and 83 % of HRR). Nearly the entire race (96.6 %)

was performed at an intensity between 70 and 90 % of

HRR. The HRmean during the 2nd lap was slightly lower as

compared to the HRmean during the 1st lap (from 162 ± 4

to 160 ± 4 beats/min, p \ 0.001). This study provided a

detailed description of the HR response to a marathon

cross-country skiing race. It showed that such race was

performed at high intensity throughout the duration of the

event, thus requiring high aerobic power.

Keywords Cross-country skiing � Endurance � Exercise

intensity

Introduction

Marathon cross-country skiing races (i.e. long at least

42 km) are becoming popular in the last years. To elu-

cidate the physiological demands of such races and help

coaches in designing more effective training programs, it

is essential to determine the exercise intensity of these

events. The intensity of the aerobic exercises (e.g. pro-

longed cross-country skiing) can be evaluated monitoring

the heart rate (HR) response. To the best of our knowl-

edge, the available information about the HR profile

during marathon cross-country skiing races is limited to

the paper by Vaananen and Vihko [1]. In this study, the

Authors only reported the average value of the HR during

a 2-day marathon (87 % of the HRmax). As a result, a

detailed analysis of the time profile of the HR response to

such skiing races is lacking. Similar to other disciplines

(e.g. on/off road cycling, running, coordinative task in

karate), contributing to fill this gap of knowledge is

desirable [2–5].

La Sgambeda Marathon is a 42-km-long race in which

athletes compete using freestyle technique. It is the first

race of the season of the FIS (International Ski Federation)

Marathon Cup, which is the World Cup for long-distance

cross-country skiers, and it is also part of the Euroloppet. It

comprises a challenging route with a peak altitude of

1,800 m above sea level.

D. Formenti (&) � A. Trecroci � L. Cavaggioni � A. Caumo �G. Alberti

Department of Biomedical Sciences for Health, Universita degli

Studi di Milano, Via G. Colombo 71, 20133 Milan, Italy

e-mail: damiano.formenti@unimi.it

A. Caumo

Research Center of Metabolism, IRCCS Policlinico San Donato

Milanese, Milan, Italy

123

Sport Sci Health

DOI 10.1007/s11332-014-0187-8

The aim of this case report was to provide a detailed

analysis of the HR profile of well-trained male amateur

skier who took part in La Sgambeda Marathon 2012.

Methods

The current research was a field descriptive case study. The

subject was a 25-year-old male skier (1.83 m; 70 kg;

20.9 kg/m2). His volume of roller-ski and cross-country ski

training from April 2012 to the race amounted to 220 h.

The subject’s resting heart rate (HRrest) and maximal heart

rate (HRmax) were measured during an incremental lab

running test before the race and resulted 60 and 180 beats/

min, respectively. The subject provided written informed

consent to participate in this study, which was approved by

the institutional review board in the spirit of the Helsinki

Declaration. To prevent energy deficit and dehydration, the

subject ingested small snacks and water during the race.

La Sgambeda Marathon is 42 km long and divided into

three parts: a preliminary short lap of 3.5 km around the

starting area (denoted as intro lap) is followed by two

almost identical laps (1st lap of 19 km and 2nd lap of

19.5 km). During the race, HR and altitude were recorded

every 1 s using a HR monitor with GPS system (RS800

by Polar Electro OY, Kempele, Finland). The recorded

data were downloaded on a PC using Polar proprietary

software and analyzed using a spreadsheet (Microsoft

Excel).

To describe the exercise intensity profile during the race,

three reference HRs were selected (corresponding to four

levels of exercise intensity). The reference HRs were cal-

culated from the ‘‘Karvonen formula’’ by multiplying the HR

reserve (HRR; HRR = HRmax-HRrest) by the factors 0.5,

0.7, 0.9 and adding these values to HRrest. As a result, four

HR zones were defined: (1) low intensity zone (HRli) during

which HR \ 120 beats/min (\50 % HRR); (2) moderate

intensity zone (HRmi) during which 120 \ HR \ 144 beats/

min (50–70 % HRR); (3) moderate-high intensity zone

(HRmhi) during which 144 \ HR \ 168 beats/min

(70–90 % HRR); (4) high intensity zone (HRhi) during

which HR [ 168 beats/min ([90 % HRR).

Fig. 1 High frequency data (every 1 s) for the case study subject

displaying the heart rate profile (top) and the ski course profile

(bottom). The vertical dashed grid lines indicate the three parts in

which the race is divided: the intro lap, the 1st lap and the 2nd lap.

The horizontal shaded band superimposed on the heart profile mark

the limits of the moderate-high intensity zone (HRmhi) during which

144 \ HR \ 168 beats/min (70–90 % HRR)

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Results

The time profiles of HR and altitude are displayed in

Fig. 1. The skier performed the race in 1 h 55 min 40 s,

with an HRmean of 160 beats/min (89 % of the HRmax and

83 % of the HRR).

Almost the whole event (96.6 %, 1 h 51 min 42 s) was

performed in the moderate-high zone, between 144 and 168

beats/min. Only 3.1 % (3 min 36 s) of the race time was

performed at high intensity (HRhi), while 0.31 % (32 s)

was spent at low intensity (HRli ? HRmi).

Figure 2 compares the distributions of HR during the

uphill and downhill parts of the race (left panel) and during

the 1st and the 2nd lap (right panel). The distribution of HR

during the uphill parts of the race was slightly skewed to

the left (skewness = -0.61), whereas the distribution of

HR during the downhill parts of the race was more sym-

metrical (skewness = -0.29). The HRmean calculated

during the downhill parts of the race was slightly but sig-

nificantly lower as compared to the HRmean during the

uphill parts of the race (158 ± 5 vs. 162 ± 4 beats/min,

p \ 0.001 with the Mann–Whitney test). The distributions

of HR during the two laps of the race showed an analogous

pattern of results. In fact, the distribution of HR during the

1st lap was left-skewed (skewness = -0.97), while the

distribution of HR during the 2nd lap tended to be more

symmetrical (skewness = -0.68). The HRmean during the

2nd lap was slightly but significantly lower as compared to

the HRmean during the 1st lap (from 162 ± 4 to 160 ± 4

beats/min, p \ 0.001 with the Mann–Whitney test).

Table 1 provides a descriptive summary of the HR

response (classified according to the four HR zones) during

the whole race and each of the three laps (intro lap, 1st lap,

2nd lap).

Discussion

The exercise intensity of the race was slightly high because

virtually the whole event (96.6 %) was performed in the

moderate-high zone. There was a statistically significant

decrease of the HRmean between the 1st and the 2nd lap.

However, the magnitude of such a decrease was very small

(from 90 to 89 % of the HRmax), thus providing evidence

that the skier was able to maintain the same intensity

throughout the whole duration of the event. These findings

are in keeping with the results of the study by Vaananen

and Vihko [1] which found that the HRmean during a

Fig. 2 Relative frequency

histograms of the distributions

of the heart rate (HR) during the

uphill and downhill parts of the

race (left panel) and during the

1st and the 2nd lap (right

panel). Each histogram bin

width was 1 beat/min

Table 1 Descriptive data on heart rate in the case study subject during the race

Whole race (42 km) Intro lap (0–3.5 km) 1st lap (3.5–22.5 km) 2nd lap (22.5–42 km)

Race time 1 h 55 min 40 s 8 min 35 s 52 min 14 s 54 min 51 s

Average speed (km/h) 21.8 24.5 21.8 20.8

HRmean (beats/min) 160 ± 5 156 ± 5 162 ± 4 160 ± 4

%HRmax 89 87 90 89

HRli (% of total race time) 0.01 (1 s) 0.2 (1 s) 0 0

HRmi (% of total race time) 0.3 (21 s) 2.1 (11 s) 0.1 (2 s) 0.2 (8 s)

HRmhi (% of total race time) 96.6 (1 h 51 min 42 s) 97.7 (8 min 23 s) 95.0 (49 min 38 s) 97.9 (53 min 41 s)

HRhi (% of total race time) 3.1 (3 min 36 s) 0 4.9 (2 min 34 s) 1.9 (1 min 2 s)

The average heart rate was reported as Mean ± SD. The actual time spent in each zone is reported within parentheses. HRli (\120 beats/min);

HRmi (120–144 beats/min); HRmhi (144–168 beats/min); HRhi ([168 beats/min)

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50-km-classic-technique race was 87 % of HRmax. Inter-

estingly, similar intensities (87.5 % of HRmax) were pre-

viously found during shorter (approximately 3 km long)

cross-country skiing races [6], thus suggesting that both

long-distance and short-distance cross-country skiing

events are performed at high level of cardiovascular

demands. On the other hand, it is worth pointing out that,

during short-distance events, the monitoring of the heart

rate, albeit essential, cannot provide an exhaustive evalu-

ation of the physiological demands and those other physi-

ological variables (e.g. lactate concentration) should be

taken into account.

In accordance with these findings, measurements of

oxygen uptake have suggested that skiers maintain

approximately 82 % VO2max for 2.5 h of skiing [7].

Interestingly, and in contrast to long-distance cross-country

skiing, a lower value of the HRmean was found in ultra-

endurance cycling (71 % of HRmax) [3]. This can be

explained by different activation in the muscles’ mass

involved (upper and lower limb in cross-country skiing,

and only lower limb in cycling) and to a longer duration of

the ultracycling event (20 h 51 min) [3].

In conclusion, this case study provided a detailed

description of the HR response to a marathon cross-country

skiing race, showing that such race was performed at a high

intensity throughout the duration of the event and required

high aerobic power. We purport the view that the approach

to data collection, presentation and analysis adopted in this

case study yields a simple and cost-effective description of

the athletic performance during this kind of competitions

and can be taken into account by ski coaches and

researchers in the design of training programs.

Further studies with larger sample sizes are necessary to

confirm the preliminary observations reported in the pres-

ent research and to fully describe the exercise intensity

during marathon cross-country skiing races.

Conflict of interest The authors declare no conflict of interest.

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