Date: 2026-01-26

# Visualize Sports Injury Data

#### 2026-01-26

    library(injurytools)
    library(ggplot2)
    library(dplyr)
    library(gridExtra)
    library(grid)
    library(knitr)

Example data: we continue exploring the cohort of Liverpool Football Club male’s first team players over two consecutive seasons, 2017-2018 and 2018-2019, scrapped from https://www.transfermarkt.com/ website1.

# A quick glance

    gg_photo(injd,
             title   = "Overview of injuries:\nLiverpool FC 1st male team during 2017-2018 and 2018-2019 seasons",
             by_date = "2 month",
             fix     = TRUE) +

      ## plus some lines of ggplot2 code..
      xlab("Follow-up date") + ylab("Players") + labs(caption = "source: transfermarkt.com") +
      theme(plot.title = element_text(face = "bold", hjust = 0.5, size = 22),
            axis.text.x.bottom = element_text(size = 13, angle = 20, hjust = 1),
            axis.text.y.left   = element_text(size = 12),
            axis.title.x       = element_text(size = 20, face = "bold", vjust = -1),
            axis.title.y       = element_text(size = 20, face = "bold", vjust = 1.8),
            legend.text        = element_text(size = 20),
            plot.caption       = element_text(face = "italic", size = 12, colour = "gray10"))

Let’s count how many injuries (red crosses in the graph) occurred and how severe they were (length of the thick black line).

    # warnings set to FALSE
    df_summary        <- calc_summary(injd)
    df_summary_perinj <- calc_summary(injd, by = "injury_type")
    # injds

Code for tidying up the tables

    df_summary |>
      mutate(incidence_new = paste0(round(incidence, 2), " (", round(incidence_lower, 2), ",", round(incidence_upper, 2), ")"),
             burden_new    = paste0(round(burden, 2), " (", round(burden_lower, 2), ",", round(burden_upper, 2), ")")) |>
      dplyr::select(2, 7, 1, incidence_new, burden_new) |>
      kable(col.names = c("N injuries", "N days lost", "Total expo", "Incidence (95% CI)", "Burden (95% CI)"),
            caption   = "Injury incidence and injury burden are reported as 100 player-matches",
            align     = "c")

    df_summary_perinj |>
      mutate(incidence_new = paste0(round(incidence, 2), " (", round(incidence_lower, 2), ",", round(incidence_upper, 2), ")"),
             burden_new    = paste0(round(burden, 2), " (", round(burden_lower, 2), ",", round(burden_upper, 2), ")")) |>
      dplyr::select(1:2, 9, 4, incidence_new, burden_new) |>
      kable(col.names = c("Type of injury", "N injuries", "N days lost", "Total expo", "Incidence (95% CI)", "Burden (95% CI)"),
            caption   = "Injury incidence and injury burden are reported as 100 player-matches",
            align     = "c")

Overall

Injury incidence and injury burden are reported as 100 player-matches
N injuries | N days lost | Total expo | Incidence (95% CI) | Burden (95% CI)
--- | --- | --- | --- | ---
82 | 2049 | 74690 | 9.88 (7.74,12.02) | 246.9 (236.21,257.59)

Overall per type of injury

Injury incidence and injury burden are reported as 100 player-matches
Type of injury | N injuries | N days lost | Total expo | Incidence (95% CI) | Burden (95% CI)
--- | --- | --- | --- | --- | ---
Bone | 11 | 173 | 74690 | 1.33 (0.54,2.11) | 20.85 (17.74,23.95)
Concussion | 16 | 213 | 74690 | 1.93 (0.98,2.87) | 25.67 (22.22,29.11)
Ligament | 9 | 596 | 74690 | 1.08 (0.38,1.79) | 71.82 (66.05,77.58)
Muscle | 25 | 735 | 74690 | 3.01 (1.83,4.19) | 88.57 (82.16,94.97)
Unknown | 21 | 332 | 74690 | 2.53 (1.45,3.61) | 40.01 (35.7,44.31)

Let’s plot the information shown in the second table in a risk matrix that displays injury incidence against injury burden.

    # warnings set to FALSE
    gg_riskmatrix(injd,
                  by = "injury_type",
                  title = "Risk matrix")

Code for further plot specifications

    # warnings set to FALSE
    palette <- c("#000000", Ligament = "#E69F00", Muscle = "#56B4E9", "#009E73",
                 Unknown = "#F0E442", "#0072B2", Bone = "#D55E00", Concussion = "#CC79A7")
    # source of the palette: http://www.cookbook-r.com/Graphs/Colors_(ggplot2)/
    theme3 <- theme(plot.title = element_text(face = "bold", hjust = 0.5, size = 20),
                    axis.text.x.bottom = element_text(size = 20),
                    axis.text.y.left = element_text(size = 20),
                    axis.title.x = element_text(size = 15),
                    axis.title.y = element_text(size = 15),
                    legend.title = element_text(size = 15),
                    legend.text = element_text(size = 15))

    gg_riskmatrix(injd,
                  by = "injury_type",
                  title = "Risk matrix") +
      scale_fill_manual(name = "Type of injury",
                        values = palette) +
      guides(fill = guide_legend(override.aes = list(size = 5))) +
      theme3

    #> `height` was translated to `width`.

# Comparing injuries occurred in 17/18 vs. 18/19

We prepare two `injd` objects:

    # warnings set to FALSE
    injd1 <- cut_injd(injd, datef = 2017)
    injd2 <- cut_injd(injd, date0 = 2018)

    ## Plot just for checking whether cut_injd() worked well
    p1 <- gg_photo(injd1, fix = TRUE, by_date = "3 months")
    p2 <- gg_photo(injd2, fix = TRUE, by_date = "3 months")
    grid.arrange(p1, p2, ncol = 2)

Let’s compute injury summary statistics for each season.

    # warnings set to FALSE
    df_summary1 <- calc_summary(injd1, quiet = T)
    df_summary2 <- calc_summary(injd2, quiet = T)

Code for tidying up the tables

    ## **Season 2017/2018**
    df_summary1 |>
      mutate(incidence_new = paste0(round(incidence, 2), " (", round(incidence_lower, 2), ",", round(incidence_upper, 2), ")"),
             burden_new    = paste0(round(burden, 2), " (", round(burden_lower, 2), ",", round(burden_upper, 2), ")")) |>
      dplyr::select(2, 7, 1, incidence_new, burden_new) |>
      kable(col.names = c("N injuries", "N days lost", "Total expo", "Incidence (95% CI)", "Burden (95% CI)"),
            caption   = "Injury incidence and injury burden are reported as 100 player-matches",
            align     = "c")

    ## **Season 2018/2019**
    df_summary2 |>
      mutate(incidence_new = paste0(round(incidence, 2), "  (", round(incidence_lower, 2), ",", round(incidence_upper, 2), ")"),
             burden_new    = paste0(round(burden, 2), "  (", round(burden_lower, 2), ",", round(burden_upper, 2), ")")) |>
      dplyr::select(2, 7, 1, incidence_new, burden_new) |>
      kable(col.names = c("N injuries", "N days lost", "Total expo", "Incidence (95% CI)", "Burden (95% CI)"),
            caption   = "Injury incidence and injury burden are reported as 100 player-matches",
            align     = "c")

Season 2017/2018

Injury incidence and injury burden are reported as 100 player-matches
N injuries | N days lost | Total expo | Incidence (95% CI) | Burden (95% CI)
--- | --- | --- | --- | ---
26 | 1141 | 31247 | 7.49 (4.61,10.37) | 328.64 (309.57,347.71)

Season 2018/2019

Injury incidence and injury burden are reported as 100 player-matches
N injuries | N days lost | Total expo | Incidence (95% CI) | Burden (95% CI)
--- | --- | --- | --- | ---
56 | 908 | 43443 | 11.6 (8.56,14.64) | 188.11 (175.87,200.34)

## - Who were the most injured players? And the most severely affected?

Player-wise statistics can be computed by `df_summay1_pl <- calc_summary(injd1, overall = FALSE)`. Then, we plot them:

    p11 <- gg_rank(injd1, line_overall = TRUE)
    p12 <- gg_rank(injd1, summary_stat = "burden", line_overall = TRUE)
    p21 <- gg_rank(injd2, line_overall = TRUE)
    p22 <- gg_rank(injd2, summary_stat = "burden", line_overall = TRUE)

    # grid.arrange(p11, p21, p12, p22, nrow = 2)

Code for further plot specifications

    theme2 <- theme(plot.title = element_text(face = "bold", hjust = 0.5, size = 26),
                    axis.text.x.bottom = element_text(size = 18),
                    axis.text.y.left = element_text(size = 13),
                    axis.title.x = element_text(size = 11, vjust = 1),
                    axis.title.y = element_text(size = 22, face = "bold", vjust = 1))

    p11 <- p11 +
      xlab("Injury incidence") +
      ylab("Player-wise incidence (injuries per 100 player-match)") +
      ggtitle("2017/2018 season") +
      scale_y_continuous(limits = c(0, 80)) + ## same x axis
      theme2 +
      theme(plot.margin = margin(0.2, 0.2, 0.2, 0.5, "cm"))
    p12 <- p12 +
      xlab("Injury burden") +
      ylab("Player-wise burden (days lost per 100 player-match)") +
      scale_y_continuous(limits = c(0, 6110)) +
      theme2 +
      theme(plot.margin = margin(0.2, 0.2, 0.2, 0.65, "cm"))

    p21 <- p21 +
      ylab("Player-wise incidence (injuries per 100 player-match)") +
      ggtitle("2018/2019 season") +
      scale_y_continuous(limits = c(0, 80)) +
      theme2
    p22 <- p22 +
      ylab("Player-wise burden (days lost per 100 player-match)") +
      scale_y_continuous(limits = c(0, 6110)) +
      theme2

    grid.arrange(p11, p21, p12, p22, nrow = 2)

## - Which injuries were more frequent? And more burdensome?

    # warnings set to FALSE
    p1 <- gg_riskmatrix(injd1, by = "injury_type",
                        title = "Season 2017/2018", add_contour = FALSE)
    p2 <- gg_riskmatrix(injd2, by = "injury_type",
                        title = "Season 2018/2019", add_contour = FALSE)

    # Print both plots side by side
    # grid.arrange(p1, p2, nrow = 1)

Code for further plot specifications

    palette <- c("#000000", Ligament = "#E69F00", Muscle = "#56B4E9", "#009E73",
                 Unknown = "#F0E442", "#0072B2", Bone = "#D55E00", Concussion = "#CC79A7")
    # source of the palette: http://www.cookbook-r.com/Graphs/Colors_(ggplot2)/
    theme3 <- theme(plot.title = element_text(face = "bold", hjust = 0.5, size = 20),
                    axis.text.x.bottom = element_text(size = 18),
                    axis.text.y.left = element_text(size = 18),
                    axis.title.x = element_text(size = 18),
                    axis.title.y = element_text(size = 18),
                    legend.title = element_text(size = 15),
                    legend.text = element_text(size = 15))

    ## Plot
    p1 <- gg_riskmatrix(injd1, by = "injury_type",
                        title = "Season 2017/2018", add_contour = T,
                        cont_max_x = 5.2, cont_max_y = 125, ## after checking the data
                        bins = 10)
    p2 <- gg_riskmatrix(injd2, by = "injury_type",
                        title = "Season 2018/2019", add_contour = T,
                        cont_max_x = 5.2, cont_max_y = 125,
                        bins = 10)

    p1 <- p1 +
      scale_x_continuous(limits = c(-0.05, 5.2)) +
      scale_y_continuous(limits = c(-0.05, 125)) +
      scale_fill_manual(name = "Type of injury",
                        values = palette) +
      guides(fill = guide_legend(override.aes = list(size = 5))) +
      theme3
    p2 <- p2 +
      scale_x_continuous(limits = c(-0.5, 5.2)) +
      scale_y_continuous(limits = c(-0.5, 125)) +
      scale_fill_manual(name = "Type of injury",
                        values = palette) + # keep the same color coding
      guides(fill = guide_legend(override.aes = list(size = 5))) +
      theme3

    grid.arrange(p1, p2, ncol = 2,
                 top = textGrob("Risk matrices", gp = gpar(fontsize = 26, font = 2))) ## for the main title

## - How many players were injured in each month?

We will create bar plots, with each bar representing the monthly prevalence2.

    gg_prevalence(injd, time_period = "monthly",
                  line_mean = TRUE)

Code for further plot specifications

    theme4 <- theme(plot.title = element_text(face = "bold", hjust = 0.5, size = 20),
                    axis.text.x = element_text(size = 13.5),
                    axis.text.y = element_text(size = 18),
                    legend.title = element_text(size = 20),
                    legend.text = element_text(size = 20),
                    strip.text = element_text(size = 20))

    gg_prevalence(injd, time_period = "monthly",
                  line_mean = TRUE,
                  title = "Monthly prevalence of sports injuries") +
      theme4

    gg_prevalence(injd, time_period = "monthly",
                  by = "injury_type", line_mean = TRUE)

Code for further plot specifications

    palette2 <- c("seagreen3", "#000000", Ligament = "#E69F00", Muscle = "#56B4E9", "#009E73",
                  Unknown = "#F0E442", "#0072B2", Bone = "#D55E00", Concussion = "#CC79A7")
    # source of the palette: http://www.cookbook-r.com/Graphs/Colors_(ggplot2)/

    gg_prevalence(injd, time_period = "monthly",
                  by = "injury_type", line_mean = TRUE,
                  title = "Monthly prevalence of each type of sports injuries") +
      scale_fill_manual(name = "Type of injury",
                        values = palette2) +
      theme4

1. These data sets are provided for illustrative purposes. We warn that they might not be accurate and could potentially include discrepancies or incomplete information compared to what actually occurred.↩︎

2. See the Note section in `?calc_prevalence()` or have a look at this section in Estimate summary statistics vignette, to better understand what the proportions refer to.↩︎